{"id":1205,"date":"2023-11-03T06:31:30","date_gmt":"2023-11-03T01:01:30","guid":{"rendered":"https:\/\/samacheer-kalvi.com\/?p=1205"},"modified":"2023-11-10T11:27:31","modified_gmt":"2023-11-10T05:57:31","slug":"samacheer-kalvi-10th-science-guide-chapter-1","status":"publish","type":"post","link":"https:\/\/samacheer-kalvi.com\/samacheer-kalvi-10th-science-guide-chapter-1\/","title":{"rendered":"Samacheer Kalvi 10th Science Guide Chapter 1 Laws of Motion"},"content":{"rendered":"

Students can download 10th Science Chapter 1 Laws of Motion Questions and Answers, Notes, Samacheer Kalvi 10th Science Guide<\/a> Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams.<\/p>\n

Tamilnadu Samacheer Kalvi 10th Science Solutions Chapter 1 Laws of Motion<\/h2>\n

Samacheer Kalvi 10th Science Laws of Motion Text Book Back Questions and Answers<\/h3>\n

I. Choose the correct answer<\/span><\/p>\n

Question 1.
\nInertia of a body depends on:
\n(a) weight of the object
\n(b) acceleration due to gravity of the planet
\n(c) mass of the object
\n(d) both (a) & (b)
\nAnswer:
\n(c) mass of the object<\/p>\n

Question 2.
\nImpulse is equals to ______ .
\n(a) rate of change of momentum
\n(b) rate of force and time
\n(c) change of momentum
\n(d) rate of change of mass.
\nAnswer:
\n(c) change of momentum<\/p>\n

\"Samacheer<\/p>\n

Question 3.
\nNewton’s III law is applicable:
\n(a) for a body is at rest
\n(b) for a body in motion
\n(c) both (a) & (b)
\n(d) only for bodies with equal masses
\nAnswer:
\n(b) for a body in motion<\/p>\n

Question 4.
\nPlotting a graph for momentum on the X-axis and time on Y-axis. Slope of momentum – time graph gives _____
\n(a) Impulsive force
\n(b) Acceleration
\n(c) Force
\n(d) Rate of force.
\nAnswer:
\n(c) Force<\/p>\n

Question 5.
\nIn which of the following sport the turning effect of force is used?
\n(a) swimming
\n(b) tennis
\n(c) cycling
\n(d) hockey
\nAnswer:
\n(c) cycling<\/p>\n

Question 6.
\nThe unit of ‘g’ is ms-2<\/sup>. It can be also expressed as:
\n(a) cm s-2<\/sup>
\n(b) N kg-1<\/sup>
\n(c) N m2<\/sup>kg-1<\/sup>
\n(d) cm2<\/sup>s-2<\/sup>
\nAnswer:
\n(a) cm s-2<\/sup><\/p>\n

Question 7.
\nOne kilogram force equals to _____ .
\n(a) 9.8 dyne
\n(b) 9.8 \u00d7 104<\/sup> N
\n(c) 98 \u00d7 104<\/sup> dyne
\n(d) 980 dyne.
\nAnswer:
\n(c) 98 \u00d7 104<\/sup> dyne<\/p>\n

Question 8.
\nThe mass of a body is measured on planet Earth as M kg. When it is taken to a planet of radius half that of the Earth then its value will be ….. kg.
\n(a) 4 M
\n(b) 2 M
\n(c) M\/4
\n(d) M
\nAnswer:
\n(c) M\/4<\/p>\n

Question 9.
\nIf the Earth shrinks to 50% of its real radius its mass remaining the same, the weight of a body on the Earth will:
\n(a) decrease by 50%
\n(b) increase by 50%
\n(c) decrease by 25%
\n(d) increase by 300%
\nAnswer:
\n(c) decrease by 25%<\/p>\n

\"Samacheer<\/p>\n

Question 10.
\nTo project the rockets which of the following principle(s) is \/ (are) required?
\n(a) Newton\u2019s third law of motion
\n(b) Newton\u2019s law of gravitation
\n(c) law of conservation of linear momentum
\n(d) both a and c.
\nAnswer:
\n(d) both a and c.<\/p>\n

II. Fill in the blanks<\/span><\/p>\n

    \n
  1. To produce a displacement …….. is required.<\/li>\n
  2. Passengers lean forward when the sudden brake is applied in a moving vehicle. This can be explained by ……….<\/li>\n
  3. By convention, the clockwise moments are taken as ……… and the anticlockwise moments are taken as ……….<\/li>\n
  4. …….. is used to change the speed of the car.<\/li>\n
  5. \u00a0A man of mass 100 kg has a weight of …….. at the surface of the Earth.<\/li>\n<\/ol>\n

    Answer:<\/p>\n

      \n
    1. force<\/li>\n
    2. inertia<\/li>\n
    3. negative, positive<\/li>\n
    4. Accelerator<\/li>\n
    5. Weight = m \u00d7 g = 100 \u00d7 9.8 = 980 N<\/li>\n<\/ol>\n

      III. State whether the following statements are true or false. Correct the statement if it is false.<\/span><\/p>\n

        \n
      1. The linear momentum of a system of particles is always conserved.<\/li>\n
      2. Apparent weight of a person is always equal to his actual weight.<\/li>\n
      3. Weight of a body is greater at the equator and less at the polar region.<\/li>\n
      4. Turning a nut with a spanner having a short handle is so easy than one with a long handle.<\/li>\n
      5. There is no gravity in the orbiting space station around the Earth. So the astronauts feel weightlessness.<\/li>\n<\/ol>\n

        Answer:<\/p>\n

          \n
        1. True<\/li>\n
        2. False – Apparent weight of a person is not always equal to his actual weight.<\/li>\n
        3. False – Weight of a body is minimum at the equator. It is maximum at the poles.<\/li>\n
        4. False – Turning a nut with a spanner having a longer handle is so easy than one with a short handle.<\/li>\n
        5. False – Astronauts are falling freely around the earth due to their huge orbital velocity.<\/li>\n<\/ol>\n

          IV. Match the following.<\/span><\/p>\n

          \"Samacheer
          \nAnswer:
          \nA. (ii)
          \nB. (Hi)
          \nC. (iv)
          \nD. (i)<\/p>\n

          \"Samacheer<\/p>\n

          V. Assertion and Reasoning.<\/span><\/p>\n

          Mark the correct choice as:
          \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
          \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of the assertion.
          \n(c) Assertion is true, but the reason is false.
          \n(d) Assertion is false, but the reason is true.
          \n1. Assertion: The sum of the clockwise moments is equal to the sum of the anticlockwise moments.
          \nReason: The principle of conservation of momentum is valid if the external force on the system is zero.
          \n2. Assertion: The value of \u2018g\u2019 decreases as height and depth increases from the surface of the Earth.
          \nReason: ‘g’ depends on the mass of the object and the Earth.
          \nAnswer:
          \n1. (b)
          \n2. (c)<\/p>\n

          VI. Answer Briefly.<\/span><\/p>\n

          Question 1.
          \nDefine inertia. Give its classification.
          \nAnswer:
          \nThe inherent property of a body to resist any change in its state of rest or the state of uniform motion, unless it is influenced upon by an external unbalanced force, is known as \u2018inertia\u2019.
          \nClassifications:<\/p>\n

            \n
          1. Inertia of rest<\/li>\n
          2. Inertia of motion<\/li>\n
          3. Inertia of direction<\/li>\n<\/ol>\n

            Question 2.
            \nClassify the types of force based on their application.
            \nAnswer:
            \nBased on the direction in which the forces act, they can be classified into two types as:<\/p>\n

              \n
            1. Like parallel forces: Two or more forces of equal or unequal magnitude acting along the same direction, parallel to each other are called like parallel forces.<\/li>\n
            2. Unlike parallel forces: If two or more equal forces or unequal forces act along with opposite directions parallel to each other, then they are called, unlike parallel forces.<\/li>\n<\/ol>\n

              Question 3.
              \nIf a 5 N and a 15 N forces are acting opposite to one another. Find the resultant force and the direction of action of the resultant force.
              \nAnswer:
              \nF1<\/sub> = 5 N
              \nF2<\/sub> = 15 N
              \n\u2234 Resultant force FR<\/sub> = F1<\/sub> – F2<\/sub>
              \n= 5 – 15 = -10 N
              \nIt acts in the direction of the force of 15 N (F2<\/sub>).<\/p>\n

              Question 4.
              \nDifferentiate mass and weight.
              \nAnswer:
              \nRatio of masses of planets is
              \nm1<\/sub> = m2<\/sub> = 2 : 3
              \nRatio of radii
              \nR1<\/sub> = R2<\/sub> = 4 : 7
              \nWe know
              \n\"Samacheer<\/p>\n

              \"Samacheer<\/p>\n

              Question 5.
              \nDefine the moment of a couple.
              \nAnswer:
              \nWhen two equal and unlike parallel forces applied simultaneously at two distinct points constitute a couple. A couple results in causes the rotation of the body. This rotating effect of a couple is known as the moment of a couple.<\/p>\n

              Question 6.
              \nState the principle of moments.
              \nAnswer:
              \nPrinciple of moments states that if a rigid body is in equilibrium on the action of a number of like (or) unlike parallel forces then the algebraic sum of the moments in the clockwise direction is equal to the algebraic sum of the moments in the anticlockwise direction.<\/p>\n

              Question 7.
              \nState Newton\u2019s second law.
              \nAnswer:
              \nThe force acting on a body is directly proportional to the rate of change of linear momentum of the body and the change in momentum takes place in the direction of the force.<\/p>\n

              Question 8.
              \nWhy a spanner with a long handle is preferred to tighten screws in heavy vehicles?
              \nAnswer:
              \nWhen a spanner is having a long handle, the turning effect of the applied force is more when the distance between the fixed edge and the point of application of force is more. Hence a spanner with a long handle is preferred to tighten screws in heavy vehicles.<\/p>\n

              Question 9.
              \nWhile catching a cricket ball the fielder lowers his hands backwards. Why?
              \nAnswer:
              \nWhile catching a cricket ball the fielder lowers his hands backwards, so increase the time during which the velocity of the cricket ball decreases to zero. Therefore the impact of force on the palm of the fielder will be reduced.<\/p>\n

              Question 10.
              \nHow does an astronaut float in a space shuttle?
              \nAnswer:
              \nAstronauts are not floating but falling freely around the earth due to their huge orbital velocity. Since spaceshuttle and astronauts have equal acceleration, they are under free fall condition. (R = 0) Hence, both the astronauts and the space station are in the state of weightlessness.<\/p>\n

              \"Samacheer<\/p>\n

              VII. Solve the given problems.<\/span><\/p>\n

              Question 1.
              \nTwo bodies have a mass ratio of 3 : 4 The force applied on the bigger mass produces an acceleration of 12 ms2<\/sup>. What could be the acceleration of the other body, if the same force acts on it.
              \nAnswer:
              \nRatio of masses m1<\/sub> : m2<\/sub> = 3 : 4
              \nAcceleration of m2<\/sub> is a2<\/sub> = 12 m\/s\u00b2
              \nForce acting of m2<\/sub> is F2<\/sub> = m2<\/sub>a2<\/sub>
              \nF2<\/sub> = 4 \u00d7 12 = 48N
              \nbut F2<\/sub> = F1<\/sub>
              \n\u2234 Force acting on m1<\/sub> is F1<\/sub> = 48N
              \n\u2234 Acceleration of m1<\/sub> = a1<\/sub> = \\(\\frac{F_1}{m_1}\\)
              \na1<\/sub> = \\(\\frac{48}{3}\\)
              \n= 16 m\/s\u00b2
              \nAcceleration of the other body ax = 16 m\/s\u00b2<\/p>\n

              Question 2.
              \nA ball of mass 1 kg moving with a speed of 10 ms-1 rebounds after a perfect elastic collision with the floor. Calculate the change in linear momentum of the ball.
              \nAnswer:
              \nGiven mass = 1 kg, speed = 10 ms-1<\/sup>
              \nInitial momentum = mu = 1 \u00d7 10 = 10 kg ms-1<\/sup>
              \nFinal momentum = -mu = -10 kg ms-1<\/sup>
              \nChange in momentum = final momentum – initial momentum = -mu – mu
              \nChange in momentum = -20 kg ms-1<\/sup><\/p>\n

              Question 3.
              \nA mechanic unscrew a nut by applying a force of 140 N with a spanner of length 40 cm. What should be the length of the spanner if a force of
              \n40 N is applied to unscrew the same nut?
              \nAnswer:
              \nForce acting on the screw F1<\/sub> = 140 N
              \nLength of a spanner d1<\/sub> = 40 \u00d7 10-2<\/sup> m
              \nSecond force applied to the screw F2<\/sub> = 40 N
              \nLet the length of spanner be d2<\/sub>
              \nAccording to the Principle of moments,
              \nF1<\/sub> \u00d7 d1<\/sub> = F2<\/sub> \u00d7 d2<\/sub>
              \n= 140 \u00d7 40 = 40 \u00d7 d2<\/sub>
              \n\u2234 d2<\/sub> = \\(\\frac{140\u00d740}{40}\\)
              \n= 140 \u00d7 10-2<\/sup> m
              \nLength of a spanner = 140 \u00d7 10-2<\/sup> m<\/p>\n

              Question 4.
              \nThe ratio of masses of two planets is 2 : 3 and the ratio of their radii is 4 : 7. Find the ratio of their accelerations due to gravity.
              \nAnswer:
              \nRatio of masses of two planets is
              \nm1<\/sub> : m2<\/sub> = 2 : 3
              \nRatio of their radii,
              \nR1<\/sub> : R2<\/sub> = 4 : 7
              \nWe know g
              \nImg 2
              \n\u2234 g1<\/sub> : g2<\/sub> = 49 : 24<\/p>\n

              \"Samacheer<\/p>\n

              VIII. Answer in Detail.<\/span><\/p>\n

              Question 1.
              \nWhat are the types of inertia? Give an example for each type.
              \nAnswer:
              \nTypes of Inertia:
              \n(i) Inertia of rest: The resistance of a body to change its state of rest is called inertia of rest.
              \nE.g.: When you vigorously shake the branches of a tree, some of the leaves and fruits are detached and they fall down (Inertia of rest).<\/p>\n

              (ii) The inertia of motion: The resistance of a body to change its state of motion is called inertia of motion.
              \nE.g.: An athlete runs some distance before jumping. Because this will help him jump longer and higher. (Inertia of motion)<\/p>\n

              (iii) Inertia of direction: The resistance of a body to change its direction of motion is called inertia of direction.
              \nE.g.: When you make a sharp turn while driving a car, you tend to lean sideways, (Inertia of direction).<\/p>\n

              Question 2.
              \nState Newton\u2019s laws of motion.
              \nAnswer:
              \n(i) Newton\u2019s First Law : States that \u201cevery body continues to be in its state of rest or the state of uniform motion along a straight line unless it is acted upon by some external force\u201d.<\/p>\n

              (ii) Newton\u2019s Second Law : States that \u201cthe force acting on a body is directly proportional to the rate of change of linear momentum of the body and the change in momentum takes place in the direction of the force\u201d.<\/p>\n

              (iii) Newton\u2019s third law : States that \u201cfor every action, there is an equal and opposite reaction. They always act on two different bodies\u201d.<\/p>\n

              Question 3.
              \nDeduce the equation of a force using Newton\u2019s second law of motion.
              \nAnswer:
              \nLet, \u2018m\u2019 be the mass of a moving body, moving along a straight line with an initial speed V. After a time interval of \u2018t\u2019, the velocity of the body changes to v due to the impact of an unbalanced external force F.
              \nInitial momentum of the body Pi<\/sub> = mu
              \nFinal momentum of the body Pf<\/sub> = mv
              \nChange in momentum \u0394p = Pi<\/sub> – Pf<\/sub> – mv – mu
              \nBy Newton\u2019s second law of motion,
              \nForce, F \u221d rate of change of momentum
              \nF \u221d change in momentum \/ time
              \nF \u221d \\(\\frac{mv-mu}{t}\\)
              \nF = \\(\\frac {km(v-u)}{t}\\)
              \nHere, k is the proportionality constant.
              \nk = 1 in all systems of units. Hence,
              \nF = \\(\\frac {m(v-u)}{t}\\)
              \nSince,
              \nacceleration = change in velocity\/time,
              \na = (v – u)\/t.
              \nHence, we have F = m \u00d7 a
              \nForce = mass \u00d7 acceleration<\/p>\n

              Question 4.
              \nState and prove the law of conservation of linear momentum.
              \nAnswer:
              \n\"Samacheer
              \nProof:
              \nLet two bodies A and B having masses m1<\/sub> and m2<\/sub> move with initial velocity u1<\/sub> and u2<\/sub> in a straight line. Let the velocity of the first body be higher than that of the second body, i.e,, u1<\/sub> > u2<\/sub>. During an interval of time t second, they tend to have a collision. After the impact, both of them move along the same straight line with a velocity v1<\/sub> and v2<\/sub> respectively.
              \nForce on body B due to A,
              \nFB<\/sub> = m2<\/sub>(v2<\/sub> – u2<\/sub>)\/t
              \nForce on body A due to B,
              \nFA<\/sub> = m1<\/sub>(v1<\/sub> – u1<\/sub>)\/t
              \nBy Newton\u2019s III law of motion,
              \nAction force = Reaction force
              \nFA<\/sub> = -FB<\/sub>
              \nm1<\/sub>(v1<\/sub> – u1<\/sub>)\/t = -m2<\/sub> (v2<\/sub> – u2<\/sub>)\/t
              \nm1<\/sub> v1<\/sub> + m2<\/sub> v2<\/sub> = m1<\/sub> u1<\/sub> + m2<\/sub> u2<\/sub>
              \nThe above equation confirms in the absence of an external force, the algebraic sum of the momentum after collision is numerically equal to the algebraic sum of the momentum before collision.
              \nHence the law of conservation of linear momentum is proved.<\/p>\n

              \"Samacheer<\/p>\n

              Question 5.
              \nDescribe rocket propulsion.
              \nAnswer:<\/p>\n

                \n
              1. Propulsion of rockets is based on the law of conservation of linear momentum as well as Newton\u2019s III law of motion.<\/li>\n
              2. Rockets are filled with fuel (either liquid or solid) in the propellant tank. When the rocket is fired, this fuel is burnt and hot gas is ejected with high speed from the nozzle of the rocket, producing a huge momentum.<\/li>\n
              3. To balance this momentum, an equal and opposite reaction force is produced in the combustion chamber, which makes the rocket project forward.<\/li>\n
              4. While in motion, the mass of the rocket gradually decreases, until the fuel is completely burnt out.<\/li>\n
              5. Since there is no net external force acting on it, the linear momentum of the system is conserved.<\/li>\n
              6. The mass of the rocket decreases with altitude, which results in the gradual increase in the velocity of the rocket.<\/li>\n
              7. At one stage, it reaches a velocity, which is sufficient to just escape from the gravitational pull of the Earth. This velocity is called escape velocity.<\/li>\n<\/ol>\n

                Question 6.
                \nState the universal law of gravitation and derive its mathematical expression.
                \nAnswer:
                \nNewton\u2019s universal law of gravitation states that every particle of matter in this universe attracts every other particle with a force. This force is directly proportional to the product of their masses and inversely proportional to the square of the distance between the centres of these masses. The direction of the force acts along the line joining the masses.<\/p>\n

                Force between the masses is always attractive and it does not depend on the medium where they are placed.
                \n\"Samacheer
                \nLet, m1<\/sub> and m2<\/sub> be the masses of two bodies A and B placed r metre apart in space
                \nForce
                \nF \u221d m1<\/sub> \u00d7 m2<\/sub>
                \nF \u221d 1\/r\u00b2
                \nOn combining the above two expressions
                \nF \u221d \\(\\frac{m_1\u00d7m_2}{r^2}\\)
                \nF = \\(\\frac{Gm_1 m_2}{r^2}\\)
                \nWhere G is the universal gravitational constant. Its value in SI unit is 6.674 \u00d7 10-11<\/sup> N m\u00b2 kg-2<\/sup>.<\/p>\n

                Question 7.
                \nGive the applications of gravitation.
                \nAnswer:<\/p>\n

                  \n
                1. Dimensions of the heavenly bodies can be measured using the gravitation law. Mass of the Earth, the radius of the Earth, acceleration due to gravity, etc. can be calculated with higher accuracy.<\/li>\n
                2. Helps in discovering new stars and planets.<\/li>\n
                3. One of the irregularities in the motion of stars is called \u2018Wobble\u2019 lead to the disturbance in the motion of a planet nearby. In this condition, the mass of the star can be calculated using the law of gravitation.<\/li>\n
                4. Helps to explain germination of roots is due to the property of geotropism, which is the property of a root responding to the gravity.<\/li>\n
                5. Helps to predict the path of the astronomical bodies.<\/li>\n<\/ol>\n

                  \"Samacheer<\/p>\n

                  IX. HOT questions.<\/span><\/p>\n

                  Question 1.
                  \nTwo blocks of masses 8 kg and 2 kg respectively lie on a smooth horizontal surface in contact with one other. They are pushed by a horizontally applied force of 15 N. Calculate the force exerted on the 2 kg mass.
                  \nAnswer:
                  \nMass of first block m1<\/sub> = 8 kg
                  \nMass of second block m2<\/sub> = 2 kg
                  \nTotal mass M = 8 + 2 = 10 kg
                  \nForce applied F = 15 N
                  \n\u2234 Acceleration a = \\(\\frac{F}{M}\\)
                  \n\\(\\frac{15}{10}\\) = 1.5 m\/s\u00b2
                  \nForce exerted on the 2 kg mass,
                  \nF = ma
                  \n= 2 \u00d7 1.5 = 3 N<\/p>\n

                  Question 2.
                  \nA heavy truck and bike are moving with the same kinetic energy. If the .mass of the truck is four times that of the bike, then calculate the ratio of their momenta. (Ratio of momenta = 1 : 2)
                  \nAnswer:
                  \nLet the mass of truck be m1<\/sub>
                  \nLet the mass of bike be m2<\/sub>
                  \nm1<\/sub> = 4m2<\/sub>
                  \n\u2234 \\(\\frac{m_1}{m_2}\\) = 4
                  \nKinetic energy K.E1<\/sub> = K.E2<\/sub>
                  \n\u2234 m2<\/sub>, \\({ v }_{ 1 }^{ 2 }\\) = m2<\/sub>\\({ v }_{ 1 }^{ 2 }\\)
                  \n\"Samacheer
                  \nRatio of momenta be P1<\/sub> : P2<\/sub>
                  \n\"Samacheer
                  \n\u2234 Ratio of their momenta = 2 : 1<\/p>\n

                  Question 3.
                  \n\u201cWearing helmet and fastening the seat belt is highly recommended for safe journey\u201d Justify your answer using Newton\u2019s laws of motion.
                  \nAnswer:
                  \n(i) According to Newton’s Second Law, when you fall from a bike on the ground with a force equal to your mass and acceleration of the bike.
                  \nAccording to Newton’s Third Law, an equal and opposite reacting force on the ground is exerted on your body. When you do not wear a helmet, this reacting force can cause fatal head injuries. So it is important to wear helmet for a safe journey.<\/p>\n

                  (ii) Inertia in the reason that people in cars need to wear seat belts. A moving car has inertia, and so do the riders inside it. When the driver applies the brakes, an unbalanced force in applied to the car. Normally the bottom of the seat applies imbalanced force friction which slows the riders down as the car slows. If the driver stops the car suddenly, however, this force is not exerted over enough time to stop the motion of the riders. Instead, the riders continue moving forward with most of their original speed because of their inertia.<\/p>\n

                  \"Samacheer<\/p>\n

                  Samacheer Kalvi 10th Science Laws of Motion Additional Important Questions and Answers<\/h3>\n

                  I. Choose the correct answer.<\/span><\/p>\n

                  Question 1.
                  \nWhen a force is exerted on an object, it can change its:
                  \n(a) state
                  \n(b) shape
                  \n(c) position
                  \n(d) all the above
                  \nAnswer:
                  \n(d) all the above<\/p>\n

                  Question 2.
                  \nWhen the train stops, the passenger moves forward, It is due to ______ .
                  \n(a) Inertia of passenger
                  \n(b) Inertia of train
                  \n(c) gravitational pull by the earth
                  \n(d) None of the above.
                  \nAnswer:
                  \n(a) Inertia of passenger<\/p>\n

                  Question 3.
                  \nForce is a …….. quantity.
                  \n(a) vector
                  \n(b) fundamental
                  \n(c) scalar
                  \n(d) none
                  \nAnswer:
                  \n(a) vector<\/p>\n

                  Question 4.
                  \nThe force of gravitation is ________ .
                  \n(a) repulsive
                  \n(b) conservative
                  \n(c) electrostatic
                  \n(d) non – conservative.
                  \nAnswer:
                  \n(b) conservative<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 5.
                  \nThe laws of motion of a body is given by:
                  \n(a) Galileo
                  \n(b) Archimedis
                  \n(c) Einstein
                  \n(d) Newton
                  \nAnswer:
                  \n(d) Newton<\/p>\n

                  Question 6.
                  \nA bodyweight 700 N on earth. What will be its weight on a planet having 1 \/ 7 of earth’s mass and half of the earth’s radius?
                  \n(a) 400 N
                  \n(b) 300 N
                  \n(c) 200 N
                  \n(d) 100 N.
                  \nAnswer:
                  \n(a) 400 N<\/p>\n

                  Question 7.
                  \nFrom the following statements write down that which is not applicable to mass of an object:
                  \n(a) It is a fundamental quantity
                  \n(b) It is measured using physical balance
                  \n(c) It is measured using spring balance
                  \n(d) It is the amount of matter.
                  \nAnswer:
                  \n(c) It is measured using spring balance<\/p>\n

                  Question 8.
                  \nNewton’s first law of motion defines:
                  \n(a) inertia
                  \n(b) force
                  \n(c) acceleration
                  \n(d) both inertia and force
                  \nAnswer:
                  \n(d) both inertia and force<\/p>\n

                  Question 9.
                  \nMechanics is divided into ____ types.
                  \n(a) one
                  \n(b) two
                  \n(c) three
                  \n(d) four.
                  \nAnswer:
                  \n(b) two<\/p>\n

                  Question 10.
                  \nWhen an object undergoes acceleration:
                  \n(a) its velocity increases
                  \n(b) its speed increases
                  \n(c) its motion is uniform
                  \n(d) a force always acts on it
                  \nAnswer:
                  \n(d) a force always acts on it<\/p>\n

                  Question 11.
                  \nOn what factor does inertia of a body depend?
                  \n(a) volume
                  \n(b) area
                  \n(c) mass
                  \n(d) density
                  \nAnswer:
                  \n(c) mass<\/p>\n

                  Question 12.
                  \n_____ deals with the motion of bodies without considering the cause of motion.
                  \n(a) Inertia
                  \n(b) Force
                  \n(c) Kinematics
                  \n(d) kinetics.
                  \nAnswer:
                  \n(c) Kinematics<\/p>\n

                  Question 13.
                  \nIf mass of an object is m, velocity v, acceleration a and applied force is F and momentum P is given by:
                  \n(a) P = m \u00d7 v
                  \n(b) P = m \u00d7 a
                  \n(c) P = \\(\\frac{m}{v}\\)
                  \n(d) P = \\(\\frac{v}{m}\\)
                  \nAnswer:
                  \n(a) P = m \u00d7 v<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 14.
                  \nWhich of the following is a vector quantity?
                  \n(a) speed
                  \n(b) distance
                  \n(c) momentum
                  \n(d) time
                  \nAnswer:
                  \n(c) momentum<\/p>\n

                  Question 15.
                  \nUnit of momentum in SI system is ______ .
                  \n(a) ms-1<\/sup>
                  \n(b) Kg ms-2<\/sup>
                  \n(c) Kg ms-1<\/sup>
                  \n(d) ms-2<\/sup>
                  \nAnswer:
                  \n(c) Kg ms-1<\/sup><\/p>\n

                  Question 16.
                  \nForce is measured based on:
                  \n(a) Newton\u2019s first law
                  \n(b) Newton\u2019s second law
                  \n(c) Newton\u2019s third law
                  \n(d) All the above
                  \nAnswer:
                  \n(b) Newton\u2019s second law<\/p>\n

                  Question 17.
                  \nForce measures rate of change of:
                  \n(a) acceleration
                  \n(b) velocity
                  \n(c) momentum
                  \n(d) distances
                  \nAnswer:
                  \n(c) momentum<\/p>\n

                  Question 18.<\/p>\n

                  The rotating or turning effect of a force about a fixed point or fixed axis is called _____ .
                  \n(a) Force
                  \n(b) momentum
                  \n(c) torque
                  \n(d) couples.
                  \nAnswer:
                  \n(c) torque<\/p>\n

                  Question 19.
                  \nThe physical quantity which is equal to the rate of change of momentum is:
                  \n(a) displacement
                  \n(b) acceleration
                  \n(c) force
                  \n(d) impulse
                  \nAnswer:
                  \n(c) force<\/p>\n

                  Question 20.
                  \nThe momentum of a massive object at rest is:
                  \n(a) very large
                  \n(b) very small
                  \n(c) zero
                  \n(d) infinity
                  \nAnswer:
                  \n(c) zero<\/p>\n

                  Question 21.
                  \nThe velocity which is sufficient to just escape from the gravitational pull of the earth is _____ .
                  \n(a) drift velocity
                  \n(b) escape velocity
                  \n(c) gradual velocity
                  \n(d) final velocity.
                  \nAnswer:
                  \n(b) escape velocity<\/p>\n

                  Question 22.
                  \nA force applied on an object is equal to:
                  \n(a) product of mass and velocity
                  \n(b) sum of mass and velocity of an object
                  \n(c) product of mass and acceleration
                  \n(d) sum of mass and acceleration
                  \nAnswer:
                  \n(c) product of mass and acceleration<\/p>\n

                  Question 23.
                  \nAction and reaction do not balance each other because they:
                  \n(a) act on the same body
                  \n(b) do not act on the same body
                  \n(c) are in opposite direction
                  \n(d) are unequal
                  \nAnswer:
                  \n(b) do not act on the same body<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 24.
                  \nThe value of variation of accelaration due to gravity (g) is ______ at the centre of the earth.
                  \n(a) one
                  \n(b) zero
                  \n(c) \u221e
                  \n(d) \\(\\frac{1}{\\infty}\\).
                  \nAnswer:
                  \n(b) zero<\/p>\n

                  Question 25.
                  \nAction and reaction forces are:
                  \n(a) equal in magnitude
                  \n(b) equal in direction
                  \n(c) opposite in direction
                  \n(d) both equal in magnitude and opposite in direction
                  \nAnswer:
                  \n(d) both equal in magnitude and opposite in direction<\/p>\n

                  Question 26.
                  \nIf mass of a body is doubled then its acceleration becomes:
                  \n(a) halved
                  \n(b) doubled
                  \n(c) thrice
                  \n(d) zero
                  \nAnswer:
                  \n(a) halved<\/p>\n

                  Question 27.
                  \nThe principle involved in the working of a jet plane is:
                  \n(a) Newton\u2019s first law
                  \n(b) Conservation of momentum
                  \n(c) Law of inertia
                  \n(d) Newton\u2019s second law
                  \nAnswer:
                  \n(b) Conservation of momentum<\/p>\n

                  Question 28.
                  \n_____ of a body is defined as the quantity of matter contained in the object.
                  \n(a) weight
                  \n(b) mass
                  \n(c) force
                  \n(d) momentum.
                  \nAnswer:
                  \n(b) mass<\/p>\n

                  Question 29.
                  \nA gun gets kicked back when a bullet is fired. It is a good example of Newton’s:
                  \n(a) gravitational law
                  \n(b) first law
                  \n(c) second law
                  \n(d) third law
                  \nAnswer:
                  \n(d) third law<\/p>\n

                  Question 30.
                  \nTo change the state or position of an object force is essential.
                  \n(a) balanced
                  \n(b) unbalanced
                  \n(c) electric
                  \n(d) elastic
                  \nAnswer:
                  \n(b) unbalanced<\/p>\n

                  Question 31.
                  \nWhen a bus starts suddenly the passengers in the standing position are pushed backwards, this action is due to:
                  \n(a) first law of motion
                  \n(b) second law of motion
                  \n(c) third law of motion
                  \n(d) conservation of momentum
                  \nAnswer:
                  \n(a) first law of motion<\/p>\n

                  Question 32.
                  \nWhen a body at rest breaks into two pieces of equal masses, then the parts will move:
                  \n(a) in same direction
                  \n(b) along different directions
                  \n(c) in opposite directions with unequal speeds
                  \n(d) in opposite directions with equal speeds
                  \nAnswer:
                  \n(d) in opposite directions with equal speeds<\/p>\n

                  Question 33.
                  \nThe principle of function of a jet aeroplane is based on:
                  \n(a) first law of motion
                  \n(b) second law of motion
                  \n(c) third law of motion
                  \n(d) all the above
                  \nAnswer:
                  \n(c) third law of motion<\/p>\n

                  Question 34.
                  \nWhich of the following has the largest inertia?
                  \n(a) pin
                  \n(b) book
                  \n(c) pen
                  \n(d) table
                  \nAnswer:
                  \n(d) table<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 35.
                  \nAn athlete runs a long path before taking a long jump to increase:
                  \n(a) energy
                  \n(b) inertia
                  \n(c) momentum
                  \n(d) force
                  \nAnswer:
                  \n(c) momentum<\/p>\n

                  Question 36.
                  \nThe weight of a person is 50 kg. The weight of that person on the surface
                  \n(a) 50 N
                  \n(b) 35 N
                  \n(c) 380 N
                  \n(d) 490 N
                  \nAnswer:
                  \n(d) 490 N<\/p>\n

                  Question 37.
                  \nWhich is incorrect statement about the action and reaction referred to Newton’s third law of motion?
                  \n(a) They are equal
                  \n(b) They are opposite
                  \n(c) They act on the same object
                  \n(d) They act on two different objects
                  \nAnswer:
                  \n(c) They act on the same object<\/p>\n

                  Question 38.
                  \nThe tendency of a force to rotate a body about a given axis is called:
                  \n(a) turning effect of a force
                  \n(b) moment of force
                  \n(c) torque
                  \n(d) all the above
                  \nAnswer:
                  \n(d) all the above<\/p>\n

                  Question 39.
                  \nThe magnitude of the moment of force is:
                  \n(a) product of force and the perpendicular distance
                  \n(b) product of force and velocity
                  \n(c) ratio of force to the acceleration
                  \n(d) ratio of force to the perpendicular distance
                  \nAnswer:
                  \n(a) product of force and the perpendicular distance<\/p>\n

                  Question 40.
                  \nIf the force rotates the body in the anticlockwise direction, then the moment is called:
                  \n(a) clockwise moment
                  \n(b) anticlockwise moment
                  \n(c) couple
                  \n(d) torque
                  \nAnswer:
                  \n(b) anticlockwise moment<\/p>\n

                  Question 41.
                  \nAnticlockwise moment is:
                  \n(a) positive
                  \n(b) negative
                  \n(c) opposite
                  \n(d) zero
                  \nAnswer:
                  \n(a) positive<\/p>\n

                  Question 42.
                  \nClockwise moment or torque is:
                  \n(a) zero
                  \n(b) always one
                  \n(c) negative
                  \n(d) positive
                  \nAnswer:
                  \n(c) negative<\/p>\n

                  Question 43.
                  \nSI unit of moment of force is:
                  \n(a) Nm-2<\/sup>
                  \n(b) Nm-1<\/sup>
                  \n(c) Ns
                  \n(d) Nm
                  \nAnswer:
                  \n(d) Nm<\/p>\n

                  Question 44.
                  \nMoment of force produces:
                  \n(a) acceleration
                  \n(b) linear motion
                  \n(c) velocity
                  \n(d) angular acceleration
                  \nAnswer:
                  \n(d) angular acceleration<\/p>\n

                  Question 45.
                  \nTwo equal and opposite forces whose lines of action do not coincide are said to constitute a:
                  \n(a) couple
                  \n(b) torque
                  \n(c) unlike force
                  \n(d) parallel force
                  \nAnswer:
                  \n(a) couple<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 46.
                  \nCouple produces:
                  \n(a) translatory motion
                  \n(b) rotatory motion
                  \n(c) translatory as well as rotatory motion
                  \n(d) neither translatory nor rotatory
                  \nAnswer:
                  \n(b) rotatory motion<\/p>\n

                  Question 47
                  \n……. is an example of couple.
                  \n(a) opening or closing a tap
                  \n(b) turning of a key in a lock
                  \n(c) steering wheel of car
                  \n(d) all the above
                  \nAnswer:
                  \n(d) all the above<\/p>\n

                  Question 48.
                  \nForce of attraction between any two objects in the universe is called:
                  \n(a) gravitational force
                  \n(b) mechanical force
                  \n(c) magnetic force
                  \n(d) electrostatic force
                  \nAnswer:
                  \n(a) gravitational force<\/p>\n

                  Question 49.
                  \nUniversal law of gravitation was given by:
                  \n(a) Archimedes
                  \n(b) Aryabhatta
                  \n(c) Kepler
                  \n(d) Newton
                  \nAnswer:
                  \n(d) Newton<\/p>\n

                  Question 50.
                  \nThe force of gravitation between two bodies does not depend on:
                  \n(a) product of their masses
                  \n(b) their separation
                  \n(c) sum of their masses
                  \n(d) gravitational constant
                  \nAnswer:
                  \n(c) sum of their masses<\/p>\n

                  Question 51.
                  \nLaw of gravitation is applicable to:
                  \n(a) heavy bodies only
                  \n(b) small sized objects
                  \n(c) light bodies
                  \n(d) objects of any size
                  \nAnswer:
                  \n(d) objects of any size<\/p>\n

                  Question 52.
                  \nThe value of gravitational constant (G) is:
                  \n(a) different at different places
                  \n(b) same at all places in the universe
                  \n(c) different at all places of earth
                  \n(d) same only at all the places of earth
                  \nAnswer:
                  \n(b) same at all places in the universe<\/p>\n

                  Question 53.
                  \nThe unit of gravitational constant is:
                  \n(a) Nm\u00b2 kg
                  \n(b) kgms-2<\/sup>
                  \n(c) Nm\u00b2 kg-2<\/sup>
                  \n(d) ms-2<\/sup>
                  \nAnswer:
                  \n(c) Nm\u00b2 kg-2<\/sup><\/p>\n

                  \"Samacheer<\/p>\n

                  Question 54.
                  \nThe weight of an object is:
                  \n(a) the quantity of matter it contains
                  \n(b) its inertia
                  \n(c) same as its mass
                  \n(d) the force with which it is attracted by the earth
                  \nAnswer:
                  \n(d) the force with which it is attracted by the earth<\/p>\n

                  Question 55.
                  \nIn vacuum, all freely failing objects have the same:
                  \n(a) speed
                  \n(b) velocity
                  \n(c) force
                  \n(d) acceleration
                  \nAnswer:
                  \n(d) acceleration<\/p>\n

                  Question 56.
                  \nThe acceleration due to gravity:
                  \n(a) has the same value everywhere in space
                  \n(b) has the same value everywhere on earth
                  \n(c) varies with the latitude on earth
                  \n(d) is greater on moon due to its smaller diameter
                  \nAnswer:
                  \n(c) varies with the latitude on earth<\/p>\n

                  Question 57.
                  \nWhen an object is thrown up, the force of gravity:
                  \n(a) is opposite to the direction of motion
                  \n(b) is in the same direction as direction of motion
                  \n(c) decreases as it rises up
                  \n(d) increases as it rises up
                  \nAnswer:
                  \n(a) is opposite to the direction of motion<\/p>\n

                  Question 58.
                  \nThe SI unit of acceleration due to gravity ‘g’ is:
                  \n(a) ms-1<\/sup>
                  \n(b) ms
                  \n(c) ms-2<\/sup>
                  \n(d) ms\u00b2
                  \nAnswer:
                  \n(c) ms-2<\/sup><\/p>\n

                  Question 59.
                  \nWhat happens to the value of ‘g’ as we go higher from surface of earth?
                  \n(a) decreases
                  \n(b) increases
                  \n(c) no change
                  \n(d) zero
                  \nAnswer:
                  \n(a) decreases<\/p>\n

                  Question 60.
                  \nMass of a body on moon is:
                  \n(a) the same as that on the earth
                  \n(b) \\(\\frac{1}{6}\\)th of that at the surface of the earth
                  \n(c) 6 times as that on the earth
                  \n(d) none of these
                  \nAnswer:
                  \n(a) the same as that on the earth<\/p>\n

                  Question 61.
                  \nAt which place is the value of ‘g’ is zero?
                  \n(a) at poles
                  \n(b) at centre of the earth
                  \n(c) at equator
                  \n(d) above the earth
                  \nAnswer:
                  \n(b) at centre of the earth<\/p>\n

                  Question 62.
                  \nThe weight of the body is maximum:
                  \n(a) at the centre of the earth
                  \n(b) on the surface of earth
                  \n(c) above the surface of earth
                  \n(d) none of the above
                  \nAnswer:
                  \n(b) on the surface of earth<\/p>\n

                  Question 63.
                  \nA rock is brought from the surface of the moon to the earth, then its:
                  \n(a) weight will change
                  \n(b) mass will change
                  \n(c) both mass and weight will change.
                  \n(d) mass and weight will remain the same
                  \nAnswer:
                  \n(a) weight will change<\/p>\n

                  Question 64.
                  \nWhy is the acceleration due to gravity on the surface of the moon is lesser than that on the surface of earth?
                  \n(a) because mass of moon is less
                  \n(b) radius of moon is less
                  \n(c) mass and radius of moon is large
                  \n(d) mass and radius of moon is less
                  \nAnswer:
                  \n(d) mass and radius of moon is less<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 65.
                  \nif the distance between two bodies is doubled, then the gravitational force between them is:
                  \n(a) halved
                  \n(b) doubled
                  \n(c) reduced to one-fourth
                  \n(d) increased by one fourth
                  \nAnswer:
                  \n(c) reduced to one-fourth<\/p>\n

                  Question 66.
                  \nThe unit newton can also be written as:
                  \n(a) kgm
                  \n(b) kgms-1<\/sup>
                  \n(c) kgms-2<\/sup>
                  \n(d) kgm-2<\/sup>s
                  \nAnswer:
                  \n(c) kgms-2<\/sup><\/p>\n

                  Question 67.
                  \nA bus starts for rest and moves after 4 seconds. Its velocity is 100 ms 1. Its uniform acceleration is:
                  \n(a) 10 ms-2<\/sup>
                  \n(b) 25 ms-2<\/sup>
                  \n(c) 400 ms-2<\/sup>
                  \n(d) 2.5 ms-2<\/sup>
                  \nAnswer:
                  \n(b) 25 ms-2<\/sup><\/p>\n

                  Question 68.
                  \nA body of mass 10 kg increases its velocity from 2 m\/s to 8 m\/s within 4 second by the application of a constant force. The magnitude of the applied force is:
                  \n(a) 1.5 N
                  \n(b) 30 N
                  \n(c) 15 N
                  \n(d) 150 N
                  \nAnswer:
                  \n(c) 15 N<\/p>\n

                  Question 69.
                  \nThe moment of force in clockwise direction is the moment in the anticlockwise direction.
                  \n(a) equal to
                  \n(b) lesser than
                  \n(c) greater than
                  \n(d) none
                  \nAnswer:
                  \n(a) equal to<\/p>\n

                  Question 70.
                  \nWhich one of the following is scalar quantity?
                  \n(a) momentum
                  \n(b) moment of force
                  \n(c) speed
                  \n(d) velocity
                  \nAnswer:
                  \n(c) speed<\/p>\n

                  Question 71.
                  \nWhich of the following changes the direction of motion of a body?
                  \n(a) momentum
                  \n(b) force
                  \n(c) energy
                  \n(d) mass
                  \nAnswer:
                  \n(b) force<\/p>\n

                  Question 72.
                  \nWhen one makes a sharp turns while driving a car he tends to lean sideways due to:
                  \n(a) inertia
                  \n(b) inertia of rest
                  \n(c) inertia of motion
                  \n(d) inertia of direction
                  \nAnswer:
                  \n(d) inertia of direction<\/p>\n

                  Question 73.
                  \nThe unit of momentum is:
                  \n(a) kg m
                  \n(b) m\/s\u00b2
                  \n(c) kg m\/s
                  \n(d) joule
                  \nAnswer:
                  \n(c) kg m\/s<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 74.
                  \nMoment of a force is given by \u03c4 =
                  \n(a) \\(\\frac{F}{d}\\)
                  \n(b) F \u00d7 2d
                  \n(c) \\(\\frac{F}{d}\\)
                  \n(d) F \u00d7 d
                  \nAnswer:
                  \n(d) F \u00d7 d<\/p>\n

                  Question 75.
                  \nWhich of the following work on the principle of torque?
                  \n(a) Gears
                  \n(b) Seasaw
                  \n(c) steering wheel
                  \n(d) all the above
                  \nAnswer:
                  \n(d) all the above<\/p>\n

                  Question 76.
                  \nThe SI unit of gravitational constant
                  \n(a) Nm\u00b2\/g
                  \n(b) Nm\u00b2kg\u00b2
                  \n(c) Nm\u00b2\/g-2<\/sup>
                  \n(d) Nmkg
                  \nAnswer:
                  \n(c) Nm\u00b2\/g-2<\/sup><\/p>\n

                  Question 77.
                  \nWhat is the value of gravitational constant?
                  \n(a) 6.674 \u00d7 10-11<\/sup> Nm\u00b2\/g-2<\/sup>
                  \n(b) 9.8 \u00d7 10-11<\/sup> Nm\u00b2\/g-2<\/sup>
                  \n(c) 6.647 \u00d7 10-11<\/sup> Nm\u00b2\/g-2<\/sup>
                  \n(d) 13.28 \u00d7 10-11<\/sup> Nm\u00b2\/g-2<\/sup>
                  \nAnswer:
                  \n(a) 6.674 \u00d7 10-11<\/sup> Nm\u00b2\/g-2<\/sup><\/p>\n

                  Question 78.
                  \nThe value of mass of the Earth is:
                  \n(a) 6.972 \u00d7 1024<\/sup> kg
                  \n(b) 6.792 \u00d7 1024<\/sup> kg
                  \n(c) 5.972 \u00d7 1024<\/sup> kg
                  \n(d) 2.936 \u00d7 1024<\/sup> kg
                  \nAnswer:
                  \n(c) 5.972 \u00d7 1024<\/sup> kg<\/p>\n

                  Question 79.
                  \nAt poles of the Earth, weight of the body is:
                  \n(a) minimum
                  \n(b) maximum
                  \n(c) zero
                  \n(d) infinity
                  \nAnswer:
                  \n(b) maximum<\/p>\n

                  Question 80.
                  \nWhere will the value of acceleration due to gravity be minimum?
                  \n(a) poles of the earth
                  \n(b) centre of the earth
                  \n(c) equator of the earth
                  \n(d) space
                  \nAnswer:
                  \n(d) space<\/p>\n

                  Question 81.
                  \nWhen an elevator is at rest:
                  \n(a) Apparent weight is greater than the actual weight
                  \n(b) Apparent weight is less than the actual weight
                  \n(c) Apparent weight is equal to the actual weight
                  \n(d) None of the above
                  \nAnswer:
                  \n(c) Apparent weight is equal to the actual weight<\/p>\n

                  Question 82.
                  \nIn a lift, apparent weight of a body is equal to zero when the lift is;
                  \n(a) at rest
                  \n(b) moving upwards
                  \n(c) moving downwards
                  \n(d) falling down freely
                  \nAnswer:
                  \n(d) falling down freely<\/p>\n

                  Question 83.
                  \nWhen the lift is moving upward with an acceleration ‘o’ the apparent weight of the body is:
                  \n(a) lesser than actual weight
                  \n(b) greater than actual weight
                  \n(c) equal to actual weight
                  \n(d) zero
                  \nAnswer:
                  \n(b) greater than actual weight<\/p>\n

                  Question 84.
                  \nWhen an elevator is moving downward, the apparent weight of a person who is in that elevator is:
                  \n(a) maximum
                  \n(b) zero
                  \n(c) minimum
                  \n(d) infinity
                  \nAnswer:
                  \n(c) minimum<\/p>\n

                  Question 85.
                  \nWhich law helps to predict the path of the astronomical bodies?
                  \n(a) Newton\u2019s law of motion
                  \n(b) Newton\u2019s law of gravitation
                  \n(c) Newton\u2019s law of cooling
                  \n(d) Pascal\u2019s law
                  \nAnswer:
                  \n(b) Newton\u2019s law of gravitation<\/p>\n

                  \"Samacheer<\/p>\n

                  II. Fill in the blanks.<\/span><\/p>\n

                  1. If force – mass \u00d7 acceleration, then momentum = ………
                  \n2. If liquid hydrogen is for rocket, then …….. is for MRI.
                  \n3. Inertia: (f) Mass then momentum: ……… Recoil of the gun: (ii) Newton’s third law: then flight of Jet Planes and Rockets: ………
                  \n4. Newton’s first law of motion: definition of force and inertia then Newton’s third law of motion: ….(i)….. while Newton’s second law of motion: ……(ii)…….
                  \n5. Newton’s first law: qualitative definition of force Newton’s second law: …..(i)…… The value of g: 9.8 ms-2 then Gravitational constant: …..(ii)……
                  \n6. Force: vector then momentum: …….(i)……. Balanced force: resultant of the two forces is zero then……(ii)…….. : resultant forces are responsible for change in position or state.
                  \n7. Momentum is the product of …….. and …….
                  \n8. To produce an acceleration of 1 m\/s\u00b2 in an object of mass 1 kg. The force required is ……… and for 3 kg of mass to produce same acceleration, the force required is ……….
                  \n9. Two or more forces are acting in an object and does not change its position, the forces are ………. and it is essential to act some ………. force, to change the state or position of an object.
                  \n10. ……… deals with bodies that are at rest under the action of force.
                  \n11. A branch of mechanics that deals with the motion of the bodies considering the cause of motion is called ………
                  \n12. If m is the mass of a body moving with velocity v then its momentum is given by P = ……..
                  \n13. A system of forces can be brought to equilibrium by applying ………. in opposite direction.
                  \n14. Torque is a ……… quantity.
                  \n15. Steering wheel transfers a torque to the wheels with ………..
                  \n16. The mathematical form of the principle of moments is ………..
                  \n17. Change in momentum takes place in the ………. of ………
                  \n18. 1 Newton = ……..
                  \n19. If a force F acts on a body for a time t’s then the impulse is ………
                  \n20. 1 kg f = ………
                  \n21. The force of attraction between two objects is directly proportional to the product of their ……. and inversely proportional to the square of the ………. between them.
                  \n22. The value of g varies with ……… and ………
                  \n23. The value of gravitational constant is ……… at all places but the value of acceleration due to gravity ………..
                  \n24. The relation between g and G is ………
                  \nAnswer:
                  \n1. mass \u00d7 velocity
                  \n2. liquid helium
                  \n3. (i) Mass and velocity, (ii) Law of conservation of momentum
                  \n4. (i) Law of conservation of momentum, (ii) Measure of force
                  \n5. (i) Quantitative definition of force, (ii) 6.673 \u00d7 10-11<\/sup> Nm\u00b2kg-2<\/sup>
                  \n6. (i) vector, (ii) imbalanced force
                  \n7. mass, velocity
                  \n8. 1 N, 3 N
                  \n9. balanced, unbalanced
                  \n10. Statics
                  \n11. kinetics
                  \n12. mv
                  \n13. equilibriant
                  \n14. vector
                  \n15. less effort
                  \n16. F1<\/sub> \u00d7 d1<\/sub> = F2<\/sub> \u00d7 d2<\/sub>
                  \n17. direction, force
                  \n18. 105<\/sup> dyne
                  \n19. I = F \u00d7 t
                  \n20. 9.8 N
                  \n21. masses, distance
                  \n22. altitude, depth
                  \n23. same, differs
                  \n24. g = \\(\\frac{GM}{R^2}\\)<\/p>\n

                  III. State whether the following statements are true or false. Correct the statement if it is false.<\/span><\/p>\n

                  1. Newton’s first law explains inertia:
                  \n2. If a motion depends on force then it is called as natural motion.
                  \n3. The resistance of a body to change its state of motion is known as inertia of motion.
                  \n4. Linear momentum = mass \u00d7 acceleration.
                  \n5. Two equal force acting in opposite directions are called unlike parallel forces.
                  \n6. If the resultant force of three force acting on body is zero then the forces are called balanced forces.
                  \n7. Torque is a scalar quantity.
                  \n8. Moment of couple = Force \u00d7 \u22a5r distance between line of action of forces
                  \n9. Principle of moments states that moment in clockwise direction = Moment in anti clockwise direction.
                  \n10. 1 Newton = 1 g cm s-2<\/sup>
                  \n11. Impulse = Force
                  \n12. Propulsion of rockets is based Newton’s third law of motion and conservation of linear momentum.
                  \n13. The value of universal gravitational constant is 6.674 \u00d7 10-11<\/sup> Nm\u00b2 kg-2<\/sup>
                  \n14. The relation between g and G is g = \\(\\frac{Gm}{R^2}\\)
                  \n15. The value of acceleration due to gravity decreases as the altitude of the body increases.
                  \n16. In a ‘free fall’ motion acceleration of the body is equal to the acceleration due to gravity.
                  \nAnswer:
                  \n1. True
                  \n2. False – If a motion does not depend on force then it is called as natural motion.
                  \n3. True
                  \n4. False – Linear momentum = mass \u00d7 velocity
                  \n5. True
                  \n6. True
                  \n7. False – Torque is a vector quantity
                  \n8. True
                  \n9. True
                  \n10. False – 1 Newton = 1 kg ms-2<\/sup>
                  \n11. False – Impulse = Change in momentum
                  \n12. True
                  \n13. True
                  \n14. False – The relation between g and G is g = \\(\\frac{GM}{R^2}\\)
                  \n15. True
                  \n16. True<\/p>\n

                  \"Samacheer<\/p>\n

                  IV. Match the following.<\/span><\/p>\n

                  Question 1.
                  \nMatch the column A with column B.
                  \n\"Samacheer
                  \nAnswer:
                  \nA. (iv)
                  \nB. (i)
                  \nC. (iii)
                  \nD. (v)
                  \nE. (ii)<\/p>\n

                  Question 2.
                  \nMatch the column A with column B.
                  \n\"Samacheer
                  \nAnswer:
                  \nA. (iv)
                  \nB. (v)
                  \nC. (ii)
                  \nD. (i)
                  \nE. (iii)<\/p>\n

                  Question 3.
                  \nMatch the column A with column B.
                  \n\"Samacheer
                  \nAnswer:
                  \nA. (ii)
                  \nB. (iv)
                  \nC. (v)
                  \nD. (i)
                  \nE. (iii)<\/p>\n

                  Question 4.
                  \nMatch the column A with column B.
                  \n\"Samacheer
                  \nAnswer:
                  \nA. (iv)
                  \nB. (v)
                  \nC. (i)
                  \nD. (ii)<\/p>\n

                  V. Assertion and Reasoning.<\/span><\/p>\n

                  Question 1.
                  \nAssertion: While travelling in a motor car we tend to remain at rest with respect to the seat.
                  \nReason: While travelling in a motor car we tend to move along the car with respect to the ground.
                  \n(a) Both Assertion and Reason are false.
                  \n(b) Assertion is true but Reason is false.
                  \n(c) Assertion is false but Reason is true.
                  \n(d) Both Assertion and Reason are true.
                  \nAnswer:
                  \n(d) Both Assertion and Reason are true.<\/p>\n

                  Question 2.
                  \nAssertion: When we kick a football it will roll over; when we kick a stone of the size of the football, it remains unmoved.
                  \nReason: Inertia of a body depends mainly on its mass.
                  \n(a) Both Assertion and Reason are true and Reason explains Assertion.
                  \n(b) Both Assertion and Reason are true but Reason doesn\u2019t explain Assertion.
                  \n(c) Both Assertion and Reason are false.
                  \n(d) Assertion is true but Reason is false.
                  \nAnswer:
                  \n(a) Both Assertion and Reason are true and Reason explains Assertion.<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 3.
                  \nAssertion: In a gun-bullet experiment, the acceleration of the gun is much lesser than the acceleration of the bullet.
                  \nReason: The gun has much smaller mass than the bullet.
                  \n(a) Both Assertion and Reason are false.
                  \n(b) Assertion is true but Reason is false.
                  \n(c) Assertion is false but Reason is true.
                  \n(d) Both Assertion and Reason are true.
                  \nAnswer:
                  \n(b) Assertion is true but Reason is false.<\/p>\n

                  Question 4.
                  \nAssertion: When a bullet is fired from a gun, the bullet moves forward, the gun moves backward.
                  \nReason: Total momentum before collision is equal to the total momentum .after collision.
                  \n(a) Both Assertion and Reason are true and Reason explains Assertion.
                  \n(b) Both Assertion and Reason are true but Reason doesn\u2019t explain Assertion.
                  \n(c) Assertion is true but Reason is false.
                  \n(d) Assertion is false but Reason is true.
                  \nAnswer:
                  \n(b) Both Assertion and Reason are true but Reason doesn\u2019t explain Assertion.<\/p>\n

                  Question 5.
                  \nAssertion: A person whose mass on earth is 125 kg will have his mass on moon as 250 kg.
                  \nReason: Mass varies from place to place.
                  \n(a) Both Assertion and Reason are true and Reason explains Assertion.
                  \n(b) Both Assertion and Reason are true but Reason doesn\u2019t explain Assertion.
                  \n(c) Both Assertion and Reason are false.
                  \n(d) Assertion is true but Reason is false.
                  \nAnswer:
                  \n(c) Both Assertion and Reason are false.<\/p>\n

                  Question 6.
                  \nAssertion: During turning a cyclist negotiates of the curve, while a man sitting in the car leans outwards of the curve.
                  \nReason: An acceleration is acting towards the centre of the curve.
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
                  \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of assertion.
                  \n(c) Assertion is true, but the reason is false.
                  \n(d) Assertion is false, but the reason is true.
                  \nAnswer:
                  \n(c) Assertion is true, but the reason is false.<\/p>\n

                  Question 7.
                  \nAssertion: On a rainy day, it is difficult to drive a car at high speed.
                  \nReason: The valve of coefficient of friction is lowered due to polishing of the surface.
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
                  \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of assertion.
                  \n(c) Assertion is true, but the reason is false.
                  \n(d) Assertion is false, but the reason is true.
                  \nAnswer:
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.<\/p>\n

                  Question 8.
                  \nAssertion: A rocket moves forward by pushing the air backwards.
                  \nReason: It derives the necessary thrust to move forwarded according to Newton’s third law of motion.
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
                  \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of assertion.
                  \n(c) Assertion is true, but the reason is false.
                  \n(d) Assertion is false, but the reason is true.
                  \nAnswer:
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.<\/p>\n

                  Question 9.
                  \nAssertion: A mass in the elevator which is falling freely, does not experience gravity.
                  \nReason: Inertial and gravitational masses have equivalence.
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
                  \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of assertion.
                  \n(c) Assertion is true, but the reason is false.
                  \n(d) Assertion is false, but the reason is true.
                  \nAnswer:
                  \n(c) Assertion is true, but the reason is false.<\/p>\n

                  Question 10.
                  \nAssertion: The intensity of gravitational field varies with respect to height and depth of a body on the Earth.
                  \nReason: The value of gravitational field intensity depends on height and depth of a body.
                  \n(a) If both the assertion and the reason are true and the reason is the correct explanation of assertion.
                  \n(b) If both the assertion and the reason are true, but the reason is not the correct explanation of assertion.
                  \n(c) Assertion is true, but the reason is false.
                  \n(d) Assertion is false, but the reason is true.
                  \nAnswer:
                  \n(d) Assertion is false, but the reason is true.<\/p>\n

                  \"Samacheer<\/p>\n

                  VI. Answer briefly.<\/span><\/p>\n

                  Question 1.
                  \nWhat is meant by mechanics? How can it be classified?
                  \nAnswer:
                  \nMechanics is the branch of physics that deals with the effect of force on bodies. It is divided into two branches namely statics and dynamics.<\/p>\n

                  Question 2.
                  \nWhat is statics?
                  \nAnswer:
                  \nStatics deals with the bodies, which are at rest under the action of forces.<\/p>\n

                  Question 3.
                  \nWhat is dynamics?
                  \nAnswer:
                  \nDynamics is the study of moving bodies under the action of forces.<\/p>\n

                  Question 4.
                  \nWhat is Kinematics?
                  \nAnswer:
                  \nKinematics deals with the motion of bodies without considering the cause of motion.<\/p>\n

                  Question 5.
                  \nWhat is Kinetics?
                  \nAnswer:
                  \nKinetics deals with the motion of bodies considering the cause of motion.<\/p>\n

                  Question 6.
                  \nDefine momentum. State its unit.
                  \nAnswer:
                  \nThe product of mass and velocity of a moving body gives the magnitude of linear momentum. It acts in the direction of the velocity of the object.
                  \nIts S.I unit is kg ms-1<\/sup>.<\/p>\n

                  Question 7.
                  \nWhat is meant by a force?
                  \nAnswer:
                  \nForce is one that changes or tends to change the state of rest or of uniform motion of a body.<\/p>\n

                  Question 8.
                  \nState the effects of force.
                  \nAnswer:<\/p>\n

                    \n
                  1. Produces or tries to produce the motion of a static body.<\/li>\n
                  2. Stops or tries to stop a moving body.<\/li>\n
                  3. Changes or tries to change the direction of motion of a moving body.<\/li>\n<\/ol>\n

                    Question 9.
                    \nWhat is resultant force?
                    \nAnswer:
                    \nWhen several forces act simultaneously on the same body, then the combined effect of the multiple forces can be represented by a single force, which is termed as \u2018resultant force\u2019.<\/p>\n

                    Question 10.
                    \nWhat are balanced forces?
                    \nAnswer:
                    \nIf the resultant force of all the forces acting on a body is equal to zero, then the body will be in equilibrium. Such forces are called balanced forces.<\/p>\n

                    \"Samacheer<\/p>\n

                    Question 11.
                    \nWhat are unbalanced forces?
                    \nAnswer:
                    \nForces acting on an object which tend to change the state of rest or of uniform motion of it are called unbalanced forces.<\/p>\n

                    Question 12.
                    \nWhat is meant by equilibriant?
                    \nAnswer:
                    \nA system can be brought to equilibrium by applying another force, which is equal to the resultant force in magnitude, but opposite in direction. Such force is called as \u2018Equilibriant\u2019.<\/p>\n

                    Question 13.
                    \nWhat is meant by couple? State few examples.
                    \nAnswer:
                    \nTwo equal and unlike parallel forces applied simultaneously at two distinct points constitute a couple. The line of action of the two forces does not coincide.
                    \nEg: Turning a tap, winding or unwinding a screw, spinning of a top, etc.<\/p>\n

                    Question 14.
                    \nA sudden application of brakes may cause injury to passengers in a car by collision with panels in front?
                    \nAnswer:
                    \nWith the application of brakes, the car slows down but our body tends to continue in the same state of motion because of inertia.<\/p>\n

                    Question 15.
                    \nWhen we are standing in a bus which begins to move suddenly, we tend to fall backwards. Why?
                    \nAnswer:
                    \nThis is because a sudden start of the bus brings motion to the bus as well as to our feet in contact with the floor of the bus. But the rest of our body opposes this motion because of its inertia.<\/p>\n

                    Question 16.
                    \nWhile travelling through a curved path, passengers in a bus tend to get thrown to one side. Justify.
                    \nAnswer:
                    \nWhen an unbalanced force is applied by the engine to change the direction of motion of the bus, passengers move to one side of the seat due to inertia of their body.<\/p>\n

                    Question 17.
                    \nDefine momentum of an object.
                    \nAnswer:
                    \nThe momentum of an object is defined as the product of its mass and velocity.<\/p>\n

                    Question 18.
                    \nDefine One newton.
                    \nAnswer:
                    \nThe amount of force required for a body of mass 1 kg produces an acceleration of 1 ms-2<\/sup>, 1 N = 1 kg ms-2<\/sup>.<\/p>\n

                    Question 19.
                    \nDefine one dyne.
                    \nAnswer:
                    \nThe amount of force required for a body of mass 1 gram produces an acceleration of 1 cm s-2<\/sup>, 1 dyne = 1 g cm s-2<\/sup>; also
                    \n1 N = 105<\/sup> dyne.<\/p>\n

                    Question 20.
                    \nWhat is unit force?
                    \nAnswer:
                    \nThe amount of force required to produce an acceleration of 1 ms-2<\/sup> in a body of mass 1 kg is called \u2018unit force\u2019.<\/p>\n

                    \"Samacheer<\/p>\n

                    Question 21.
                    \nWhat are the values of 1 kg f and 1 g f.
                    \nAnswer:
                    \n1 kg f= 1 kg \u00d7 9.8 m s-2<\/sup> = 9.8 N;
                    \n1 g f = 1 g \u00d7 980 cm s-2<\/sup> = 980 dyne<\/p>\n

                    Question 22.
                    \nWhat is meant by impulsive force?
                    \nAnswer:
                    \nA large force acting for a very short interval of time is called as \u2018Impulsive force\u2019.<\/p>\n

                    Question 23.
                    \nWhat is meant by impulse?
                    \nAnswer:
                    \nWhen a force F acts on a body for a period of time t, then the product of force and time is known as \u2018impulse\u2019 represented by \u2018J\u2019
                    \nImpulse, J = F \u00d7 t<\/p>\n

                    Question 24.
                    \nProve that impulse is equal to the magnitude of change in momentum.
                    \nAnswer:
                    \nBy Newton\u2019s second law,
                    \nF = \u0394P\/t (\u0394 refers to change)
                    \n\u0394P = F \u00d7 t
                    \nJ = \u0394P
                    \nF \u00d7 t = \u0394P
                    \nImpulse is also equal to the magnitude of change in momentum. Its unit is kg ms-1<\/sup> or N s.<\/p>\n

                    Question 25.
                    \nHow can the change in momentum be achieved?
                    \nAnswer:
                    \nChange in momentum can be achieved in two ways. They are:<\/p>\n

                      \n
                    1. A large force acting for a short period of time and<\/li>\n
                    2. A smaller force acting for a longer period of time.<\/li>\n<\/ol>\n

                      Question 26.
                      \nState an example for change in momentum.
                      \nAnswer:
                      \nAutomobiles are fitted with springs and shock absorbers to reduce jerks while moving on uneven roads.<\/p>\n

                      Question 27.
                      \nA spring balance is fastened to a wall and another spring balance is attached to its hole and is pulled steadily. Do both the spring balances show different readings on their scales. Give reason.
                      \nAnswer:
                      \nNo, both the spring balances show same reading. Because both action and reaction are equal and opposite.<\/p>\n

                      Question 28.
                      \nWhen a gun is fired it recoils, Give reason.
                      \nAnswer:
                      \nWhen a gun is fired it exerts forward force on the bullet. The bullet exerts an equal and opposite reaction force on the gun. This results in the recoil of the gun.<\/p>\n

                      Question 29.
                      \nAction and reaction are equal and opposite. But they do not cancel each other. Give reason.
                      \nAnswer:
                      \nThey do not cancel each other because they never act on the same body. Since they act on different bodies, they do not cancel each other.<\/p>\n

                      Question 30.
                      \nWhy does a cricket player, pulls his arms back with the ball while catching a ball?
                      \nAnswer:
                      \n(i) The cricket player stops the speeding ball suddenly in a very short time. The high value of velocity of the ball will be decreased to zero, in a very short time and it will result in a high retardation.
                      \n(ii) When the player pulls his arms with the ball, he increases the value of time and so retardation is also decreased and retardation force is lesser than before and the palm of player is not hurt.<\/p>\n

                      \"Samacheer<\/p>\n

                      Question 31.
                      \nWhen a sailor jumps forward, the boat moves backward. State the action and reaction in the above case.
                      \nAnswer:
                      \nAction – a sailor jumps forward.
                      \nReaction – movement of the boat.<\/p>\n

                      Question 32.
                      \nIt is easier to stop a tennis ball than a cricket ball moving with the same velocity.
                      \nAnswer:
                      \nThis is because the mass of tennis ball is less than the cricket ball. So it has lesser momentum and hence smaller force is required to stop the tennis ball.<\/p>\n

                      Question 33.
                      \nDefine moment of force.
                      \nAnswer:
                      \nThe magnitude of the moment of force about a point is defined as the product of the magnitude of force and perpendicular distance of the point from the line of action of the force.<\/p>\n

                      Question 34.
                      \nDraw the diagram of a couple.
                      \nAnswer:
                      \n\"Samacheer<\/p>\n

                      Question 35.
                      \nWhat do you know about moment of a couple?
                      \nAnswer:
                      \nMoment of a couple is the product of force and perpendicular distance between the line of action of forces.
                      \nM = F \u00d7 S<\/p>\n

                      Question 36.
                      \nIt is easier to open a door by applying the force at the free end. Justify.
                      \nAnswer:
                      \n(i) If the force is applied at the handle of the door to open it, only small force is required. That means larger the perpendicular distance, lesser is the force needed to turn the body.<\/p>\n

                      (ii) From this it is easy to conclude that the turning effect of a body about an axis depends not only on the magnitude of the force but also on the perpendicular distance of the line of action of the applied force from the axis of rotation.<\/p>\n

                      Question 37.
                      \nA force can rotate a nut when applied by a wrench.
                      \nAnswer:
                      \n(a) What is meant by moment of force?
                      \nAnswer:
                      \nThe turning effect of force acting on a body about an axis is called the moment of force.<\/p>\n

                      (b) Name the factors on which the turning effect of a force depend on.
                      \nAnswer:
                      \nTurning effect of force depends on-<\/p>\n

                        \n
                      1. The magnitude of the force applied and<\/li>\n
                      2. The distance of line of action of the force from the axis of rotation.<\/li>\n<\/ol>\n

                        Question 38.
                        \nWhat is meant by weightlessness?
                        \nAnswer:
                        \nWhenever a body or a person falls freely under the action of Earth\u2019s gravitational force alone, it appears to have zero weight. This state is referred to as \u2018weightlessness\u2019.<\/p>\n

                        Question 39.
                        \nWhat is meant by moment of a force?
                        \nAnswer:
                        \nThe turning effect of force acting on a body about an axis is called moment of force.<\/p>\n

                        Question 40.
                        \nWhat is meant by gravitational force?
                        \nAnswer:
                        \nThe gravitational force is the force of attraction between objects in the universe.<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 41.
                        \nIn which direction does gravitational force act?
                        \nAnswer:
                        \nThe gravitational force acts along the line joining the centres of two objects.<\/p>\n

                        Question 42.
                        \n(a) When a horse suddenly starts running, the rider falls backward. Give reason.
                        \nAnswer:
                        \nThis is because the lower part of the rider which is in contact with the horse, comes into motion. While his upper part tends to remain at rest due to inertia.<\/p>\n

                        (b) Coin falls into the tumbler when the card is given a sudden jerk. State the fact that is utilized in this illustration.
                        \nAnswer:
                        \ninertia.<\/p>\n

                        Question 43.
                        \n(a) Why it is difficult to walk on a slippery floor or sand?
                        \nAnswer:
                        \nBecause we are unable to push (action) such a ground sufficiently hard. As a result, the force of reaction is not sufficient to help us to move forward.<\/p>\n

                        (b) State the law related to this.
                        \nAnswer:
                        \nNewton\u2019s third law of motion.<\/p>\n

                        Question 44.
                        \nState the numerical value and unit of gravitational constant.
                        \nAnswer:
                        \nThe numerical value of gravitational constant is 6.673 \u00d7 10-11<\/sup> Nm\u00b2 kg-2<\/sup>.
                        \nIts unit is Nm\u00b2 kg-2<\/sup>.<\/p>\n

                        Question 45.
                        \nWhat is meant by acceleration due gravity?
                        \nAnswer:
                        \nThe acceleration produced in a body on account of the force of gravity is called acceleration due to gravity.<\/p>\n

                        Question 46.
                        \nWrite the expression of acceleration due to gravity.
                        \nAnswer:
                        \nAcceleration due to gravity g = \\(\\frac{GM}{R^2}\\)
                        \nwhere G is gravitational constant.
                        \nM is the mass of the earth.
                        \nR is radius of the earth.<\/p>\n

                        Question 47.
                        \nDeduce the value of mass of earth.
                        \nAnswer:
                        \nMass of earth M = \\(\\frac{gR^2}{G}\\)
                        \ng = 9.8 m\/s\u00b2
                        \nR = 6.38 \u00d7 106<\/sup> m
                        \nG = 6.673 \u00d7 10-11<\/sup> Nm\u00b2 kg-2<\/sup>
                        \n\"Samacheer
                        \n= 5.98 \u00d7 1024<\/sup> kg<\/p>\n

                        Question 48.
                        \nWhat happens to the gravitational force between two objects if the masses of both objects are doubled?
                        \nAnswer:
                        \nIf the masses of both objects are doubled, then gravitational force between them will be increased to four times.<\/p>\n

                        Question 49.
                        \nThe mass of a body is 60 kg. What will be its mass when it is placed on the moon?
                        \nAnswer:
                        \nThe mass of a body on the moon is 60 kg. There will be no change in mass because it is still made up of same amount of matter.<\/p>\n

                        Question 50.
                        \nWhen an object is taken to the moon, is there any change in weight?
                        \nAnswer:
                        \nYes. The weight of a object will be decreased because the gravitational force is weak i.e., the value of acceleration due to gravity becomes less on the moon.<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 51.
                        \nGravitational force acts on all objects is proportional to their masses. But a heavy object falls slower than a light object. Give reason.
                        \nAnswer:
                        \nIt is true that gravitational force between all objects are in proportion to their masses. But in free fall of objects, acceleration produced in a body is due to gravitational force is independent of mass of object that\u2019s why a heavy object does not fall faster.<\/p>\n

                        Question 52.
                        \nA falling apple is attracted towards the earth.
                        \n(a) Does the apple attract the earth?
                        \nAnswer:
                        \nYes. According to Newton\u2019s third Law. The apple attracts the earth.<\/p>\n

                        (b) Why doesn\u2019t earth move towards an apple?
                        \nAnswer:
                        \nAccording to Newton\u2019s second Law, for a given force, acceleration a \u221d \\(\\frac{1}{m}\\). Here mass of an apple is negligibly small compared to earth. So we cannot see the earth moving towards an apple.<\/p>\n

                        Question 53.
                        \nObserve the figure and write the answer:
                        \nAnswer:
                        \n\"Samacheer
                        \n(a) The force which balance A exerts on balance B is called …….
                        \nAnswer:
                        \nThe force which balance A exerts on balance B is called action.<\/p>\n

                        (b) The force of balance B on balance A is called ……..
                        \nAnswer:
                        \nThe force of balance B on balance A is called opposite reaction.<\/p>\n

                        Question 54.
                        \nWhat is meant by apparent weight?
                        \nAnswer:
                        \nApparent weight is the weight of the body acquired due to the action of gravity and other external forces acting on the body.<\/p>\n

                        Question 55.
                        \nWhat is meant by free fall?
                        \nAnswer:
                        \nWhen the person in a lift moves down with an acceleration (a) equal to the , acceleration due to gravity (g), i.e., when a = g, this motion is called as \u2018free fall\u2019. Here, the apparent weight (R = m (g – g) = 0) of the person is zero.<\/p>\n

                        \"Samacheer<\/p>\n

                        VII. Solve the given problems.<\/span><\/p>\n

                        Question 1.
                        \nThe ratio of masses of two bodies is 1 : 3 and the ratio of applied forces on them is 4 : 9. Calculate the ratio of their accelerations.
                        \nAnswer:
                        \nRatio of masses m1<\/sub> : m2<\/sub> = 1 : 3
                        \nRatio of applied forces F1<\/sub> : F2<\/sub> = 4 : 9
                        \nAccelerations a = \\(\\frac{F}{m}\\)
                        \nAcceleration of first body,
                        \na1<\/sub> = \\(\\frac{F_1}{m_1}\\)
                        \n= \\(\\frac{4}{1}\\) = 4
                        \nAcceleration of second body,
                        \na2<\/sub> = \\(\\frac{F_2}{m_2}\\)
                        \nRatio of their accelerations is 4 : 3<\/p>\n

                        Question 2.
                        \nWhat is acceleration produced by a force of 12 N exerted on an object of mass 3 kg?
                        \nAnswer:
                        \nF = 12 N; m = 3 kg ; a = ?
                        \nF = ma; a = F\/m = \\(\\frac{4}{1}\\) = 4 m\/s\u00b2
                        \nThe acceleration produced a = 4 m\/s\u00b2.<\/p>\n

                        Question 3.
                        \nA certain force exerted for 1.2 s raises the speed of an object from 1.8 m\/s to 4.2 m\/s. Later, the same force is applied for 2 s. How much does the speed change in 2 s.
                        \nAnswer:
                        \nt = 1.2 s; u = 1.8 m\/s; v = 4.2 m\/s
                        \nacceleration a = \\(\\frac{v-u}{t}\\)
                        \n= \\(\\frac{4.2-1.8}{1.2}\\) = \\(\\frac{2.4}{1.2}\\)
                        \n= 2 m\/s\u00b2
                        \nNow, the force applied is the same, it will produce the same acceleration.
                        \nChange in speed = acceleration \u00d7 time for which force is applied.
                        \n= 2 \u00d7 2 = 4 m\/s
                        \nChange in speed = 4 m\/s.<\/p>\n

                        Question 4.
                        \nA constant force acts on an object of mass 10 kg for a duration of 4 s. It increases the objects velocity from 2 ms-1<\/sup> to 8 ms-1<\/sup>. Find the magnitude of the applied force.
                        \nAnswer:
                        \nMass of an object m = 10 kg
                        \nInitial velocity u = 2 ms-1<\/sup>
                        \nFinal velocity v = 8 ms-1<\/sup>
                        \nWe know, force F = \\(\\frac{m(v-u)}{t}\\)
                        \nF = \\(\\frac{10(8-2)}{4}\\)
                        \n= \\(\\frac{10\u00d76}{4}\\)
                        \n= 15 N<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 5.
                        \nWhich would require a greater force for accelerating a 2 kg of mass at 4 ms-2<\/sup> or a 3 kg mass at 2 ms-2<\/sup>?
                        \nAnswer:
                        \nWe know, force F = ma
                        \nGiven m1<\/sub> = 2 kg a1<\/sub> = 4 ms-2<\/sup>
                        \nm2<\/sub> = 3 kg a2<\/sub> = 2 ms-2<\/sup>
                        \nF1<\/sub> = m1<\/sub> a1<\/sub> = 2 \u00d7 4 = 8 N
                        \nF2<\/sub> = m2 <\/sub>a2<\/sub> = 3 \u00d7 2 = 6 N
                        \n\u2234 F1<\/sub> > F2<\/sub>.
                        \nThus, accelerating 2 kg mass at 4 ms-2<\/sup>\u00a0would require a greater force.<\/p>\n

                        Question 6.
                        \nA bullet of mass 15 g is horizontally fired with a velocity 100 ms-1<\/sup> from a pistol of mass 2 kg. What is the recoil velocity of the pistol?
                        \nAnswer:
                        \nThe mass of the bullet, m1<\/sub> = 15 g = 0.015 kg
                        \nMass of the pistol, m2<\/sub> = 2 kg
                        \nInitial velocity of the bullet, u1<\/sub> = 0
                        \nInitial velocity of the pistol, u2<\/sub> = 0
                        \nFinal velocity of the bullet, v1<\/sub> = + 100 ms-1<\/sup>
                        \n(The direction of the bullet is taken from left to right-positive, by convention) Recoil velocity of the pistol = v2<\/sub>
                        \nTotal momentum of the pistol and bullet before firing.
                        \n= m1<\/sub> u1<\/sub> + m2<\/sub> u1<\/sub>
                        \n= (0.015 \u00d7 0) + (2 \u00d7 0)
                        \n= 0
                        \nTotal momentum of the pistol and bullet after firing.
                        \n= m1<\/sub> v1<\/sub> + m2<\/sub> v2<\/sub>
                        \n= (0.015 \u00d7 100) + (2 \u00d7 v2<\/sub>)
                        \n= 1.5 + 2v2<\/sub>
                        \nAccording to the law of conservation of momentum,
                        \nTotal momentum after firing = Total momentum before firing.
                        \n1.5 + 2v2<\/sub> = 0
                        \n2v2<\/sub> = -1.5
                        \nv2<\/sub> = – 0.75 ms-1<\/sup>
                        \nNegative sign indicates that the direction in which the pistol would recoil is opposite to that of the bullet, that is, right to left.<\/p>\n

                        Question 7.
                        \nA 10 g bullet is shot from a 5 kg gun with a velocity of 400 m\/s. what is the speed of recoil of the gun?
                        \nAnswer:
                        \nMass of bullet, m1<\/sub> = 10 g
                        \n= 10 \u00d7 10-3<\/sup> kg = 10-2<\/sup> kg
                        \nMass of gun, m2<\/sub> = 5 kg
                        \nVelocity of bullet, v1<\/sub> = 400 m\/s
                        \nspeed of recoil of gun v2<\/sub> = ?
                        \nTotal momentum of bullet and gun after firing = total momentum before firing.
                        \nm1<\/sub> v1<\/sub> + m2<\/sub> v2<\/sub> = 0
                        \nv2<\/sub> = –\\(\\frac{m_1 v_1}{m_2}\\)
                        \n= \\(\\frac{-10_{-2}\u00d7400}{5}\\) = -0.8 m\/’s.
                        \nThe speed of recoil of the gun v2<\/sub> = -0.8 m\/’s.
                        \nNegative sign shows that the gun moves in a direction opposite to that of the bullet.<\/p>\n

                        Question 8.
                        \nThe figure represents two bodies of masses 10 kg and 20 kg, moving with an initial velocity of 10 ms-1<\/sup> and 5 ms-1<\/sup> respectively. They collide with each other. After collision, they move with velocities 12 ms-1<\/sup> and 4 ms-1<\/sup> respectively. The time of collision is 2 s. Now calculate F2<\/sub> and F2<\/sub>.
                        \nAnswer:
                        \n\"Samacheer
                        \nm1<\/sub> = 10 kg
                        \nm2<\/sub> = 20 kg
                        \nu1<\/sub> = 10 ms-1<\/sup>
                        \nu2<\/sub> = 5 ms-1<\/sup>
                        \nv1<\/sub> = 12 ms-1<\/sup>
                        \nv2<\/sub> = 4 ms-1<\/sup>
                        \nTime of collision, t = 2 s
                        \n\u2234 Force acting on 20 kg object
                        \nF1<\/sub> = m2<\/sub> (\\(\\frac{v_2-u_2}{t}\\))
                        \n= 20(\\(\\frac{4-5}{2}\\))
                        \nF1<\/sub> = -10 N
                        \nForce acting on 10 kg object
                        \nF2<\/sub> = m1<\/sub> (\\(\\frac{v_1-u_1}{t}\\))
                        \n= 10(\\(\\frac{12-10}{2}\\))
                        \nF2<\/sub> = 10 N<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 9.
                        \nThe mass of an object is 5 kg. What is its weight on the earth?
                        \nAnswer:
                        \nMass, m = 5 kg
                        \nAcceleration due to gravity,
                        \ng = 9.8 ms-2<\/sup>
                        \nWeight, W = m \u00d7 g
                        \nW = 5 \u00d7 9.8 = 49 N
                        \nTherefore, the weight of the object is 49 N.<\/p>\n

                        Question 10.
                        \nCalculate the force of gravitation between two objects of masses 80 kg and 120 kg kept at a distance of 10 m from each other. Given, G = 6.67 \u00d7 10-11<\/sup> Nm\u00b2 \/ kg\u00b2.
                        \nAnswer:
                        \nm1<\/sub> = 80 kg, m2<\/sub> = 120 kg, r = 10 m,
                        \nG = 6.67 \u00d7 10-11<\/sup> Nm\u00b2 \/ kg\u00b2, F = ?
                        \n\"Samacheer
                        \n= 64.032 \u00d7 10-10<\/sup> N
                        \nThe force of gravitation between two objects = 64.032 \u00d7 10-10<\/sup> N.<\/p>\n

                        Question 11.
                        \nCalculate the value of acceleration due to gravity on moon. Given mass of moon = 7.4 \u00d7 1022<\/sup> kg. radius of moon = 1740 km.
                        \nAnswer:
                        \n\"Samacheer
                        \n= 1.63 ms2<\/sup>
                        \nThe acceleration due to gravity = 1.63 ms-2<\/sup>.<\/p>\n

                        Question 12.
                        \nState Newton\u2019s law of gravitation. Write an expression for acceleration due to gravity on the surface of the earth. If the ratio of acceleration due to gravity of two heavenly bodies is 1 : 4 and the ratio of their radii is 1 : 3, what will be the ratio of their masses?
                        \nAnswer:
                        \nNewton\u2019s law of gravitation states that every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
                        \nF = \\(\\frac{Gm_{1}m_{2}}{d^{2}}\\)
                        \nAcceleration due to gravity g = \\(\\frac{GM}{R^{2}}\\)
                        \nWhere G is gravitational constant
                        \nM is the mass of the earth
                        \nR is radius of the earth
                        \nRatio of acceleration due to gravity = 1 : 4
                        \nRatio of radii of two bodies = 1 : 3
                        \nAcceleration due to gravity is g
                        \n\"Samacheer
                        \nDividing Equation (1) by equation (2) we get
                        \n\"Samacheer
                        \n\u2234 M1<\/sub> : M2<\/sub> = 1 : 36
                        \n\u2234 Ratio of their masses = 1 : 36<\/p>\n

                        Question 13.
                        \nA bomb of mass 3 kg, initially at rest, explodes into two parts of 2 kg and 1 kg. The 2 kg mass travels with a velocity of 3 m\/s. At what velocity will the 1 kg mass travel?
                        \nAnswer:
                        \nMass of a bomb m = 3 kg
                        \nInitial velocity of the bomb v = 0
                        \nMass of the first part m1<\/sub> = 2 kg
                        \nVelocity of the first part v1<\/sub>= 3 m\/s
                        \nMass of the second part m2<\/sub> = 1 kg
                        \nLet the velocity of the second part be v2<\/sub>.
                        \nBy the law of conservation of momentum
                        \nmv = m1<\/sub> v1<\/sub> + m2<\/sub> v2<\/sub>
                        \n3 \u00d7 0 = 2 \u00d7 3 + 1 \u00d7 v2<\/sub>
                        \n0 = 6 + v2<\/sub>
                        \n\u2234 v2<\/sub> = -6 m\/s
                        \nVelocity of the 1 kg mass = -6 m\/s<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 14.
                        \nTwo ice skaters of weight 60 kg and 50 kg are holding the two ends of a rope. The rope is taut. The 60 kg man pulls the rope with 20 N force. What will be the force exerted by the rope on the other person? What will be their respective acceleration?
                        \nAnswer:
                        \nMass of first ice skater = 50 kg
                        \nMass of second ice skater = 60 kg
                        \nForce applied by second ice skater = 20 N
                        \nWhen the rope is taut, the force exerted by the rope on the other person is 20 N.
                        \n\"Samacheer
                        \n= 0.33 m\/s\u00b2<\/p>\n

                        VIII. Answer in detail.<\/span><\/p>\n

                        Question 1.
                        \nExplain the types of forces.
                        \nAnswer:
                        \nBased on the direction in which the forces act, they can be classified into two types as:
                        \n1. Like parallel forces : Two or more forces of equal or unequal magnitude acting along the same direction, parallel to each other are called like parallel forces.
                        \n2. Unlike parallel forces : If two or more equal forces or unequal forces act along opposite directions parallel to each other, then they are called unlike parallel forces.<\/p>\n

                        Question 2.
                        \nTabulate the action of forces with their resultant and diagram.
                        \nAnswer:
                        \n\"Samacheer<\/p>\n

                        Question 3.
                        \nExplain the applications of torque.
                        \nAnswer:
                        \n1. Gears : A gear is a circular wheel with teeth around its rim. It helps to change the speed of rotation of a wheel by changing the torque and helps to transmit power.<\/p>\n

                        2. Seasaw : Most of you have played on the seasaw. Since there is a difference in the weight of the persons sitting on it, the heavier person lifts the lighter person. When the heavier person comes closer to the pivot point (fulcrum) the distance of the line of action of the force decreases. It causes less amount of torque to act on it. This enables the lighter person to lift the heavier person.<\/p>\n

                        3. Steering Wheel : A small steering wheel enables you to manoeuore a car easily by transferring a torque to the wheels with less effort.<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 4.
                        \nState and explain principle of moments.
                        \nAnswer:
                        \nWhen a number of like or unlike parallel forces act on a rigid body and the body is in equilibrium, then the algebraic sum of the moments in the clockwise direction is equal to the algebraic sum of the moments in the anticlockwise direction. In other words, at equilibrium, the algebraic sum of the moments of all the individual forces about any point is equal to zero.
                        \n\"Samacheer
                        \nIn the illustration given in figure, the force F1<\/sub> produces an anticlockwise rotation at a distance d1<\/sub> from the point of pivot P (called fulcrum) and the force F2<\/sub> produces a clockwise rotation at a distance d2<\/sub> from the point of pivot P. The principle of moments can be written as follows:
                        \nMoment of clockwise direction = Moment of anticlockwise direction
                        \nF1<\/sub> \u00d7 d1<\/sub> = F2<\/sub> \u00d7 d2<\/sub><\/p>\n

                        Question 5.
                        \nExplain the illustrations for Newton\u2019s third law of motion briefly.
                        \nAnswer:
                        \nNewton\u2019s third law states that \u2018for every action, there is an equal and opposite reaction.They always act on two different bodies.
                        \nIf a body A applies a force FA<\/sub> on a body B, then the body B reacts with force FB<\/sub> on the body A, which is equal to FA<\/sub> in magnitude, but opposite in direction. FB<\/sub> = -FA<\/sub>
                        \nEg:
                        \n(i) When birds fly they push the air downwards with their wings (Action) and the air pushes the bird upwards(Reaction).
                        \n(ii) When a person swims he pushes the water using the hands backwards (Action), and the water pushes the swimmer in the forward direction (Reaction).
                        \n(iii) When you fire a bullet, the gun recoils backward and the bullet is moving forward (Action) and the gun equalises this forward action by moving backward (Reaction).<\/p>\n

                        Question 6.
                        \nDerive the relation between acceleration due to gravity (g) and Gravitational constant G.
                        \nAnswer:
                        \n\"Samacheer
                        \nWhen a body is at rests on the surface of the Earth, it is acted upon by the gravitational force of the Earth. Let us compute the magnitude of this force in two ways. Let, M be the mass of the Earth and m be the mass of the body. The entire mass of the Earth is assumed to be concentrated at its centre. The radius of the Earth is R = 6378 km = 6400 km approximately. By Newton\u2019s law of gravitation, the force acting on the body is given by
                        \nF = \\(\\frac{GMm}{R^2}\\)
                        \nHere, the radius of the body considered is negligible when compared with the Earth\u2019s radius. Now, the same force can be obtained from Newton\u2019s second law of motion.
                        \nAccording to this law, the force acting on the body is given by the product of its mass and acceleration (called as weight). Here, acceleration of the body is under the action of gravity hence a = g
                        \nF = ma = mg …….. (1)
                        \nF = weight = mg ……… (2)
                        \nComparing equations (1) and (2), we get
                        \nmg = \\(\\frac{GMm}{R^2}\\)
                        \nAcceleration due to gravity g = \\(\\frac{GM}{R^2}\\)<\/p>\n

                        Question 7.
                        \nTabulate the apparent weight of person moving in a lift when lift is
                        \n(i) moving upwards
                        \n(ii) moving downwards
                        \n(iii) at rest
                        \n(iv) falling down freely.
                        \nAnswer:
                        \n\"Samacheer<\/p>\n

                        \"Samacheer<\/p>\n

                        IX. HOT Questions<\/span><\/p>\n

                        Question 1.
                        \nWhat gives the measure of inertia?
                        \nAnswer:
                        \nMass of a body gives the measure of inertia.<\/p>\n

                        Question 2.
                        \nIs any external force required to keep a body in uniform motion?
                        \nAnswer:
                        \nNo, external force is not required to keep a body in uniform motion.<\/p>\n

                        Question 3.
                        \nWhich law of motion gives the measure of force?
                        \nAnswer:
                        \nNewton\u2019s second law of motion.<\/p>\n

                        Question 4.
                        \nWrite the second law of motion in vector form.
                        \nAnswer:
                        \n\\(\\vec { F } =m\\vec { a }\\)
                        \nWhere, \\(\\vec { F }\\) – force, m – mass, \\(\\vec { a }\\) – acceleration.<\/p>\n

                        Question 5.
                        \nWhat is the net force acting on a cork that floats on water? Why?
                        \nAnswer:
                        \nThe net force is zero, because the weight of the cork is balanced by the upthrust of water on it.<\/p>\n

                        Question 6.
                        \nWhat is the relation between newton and dyne?
                        \nAnswer:
                        \n1 newton = 105 dyne<\/p>\n

                        Question 7.
                        \nA person is standing on a weighing machine placed nearly a door. What will be the effect of the reading of the machine if a person presses the edge of the door upward?
                        \nAnswer:
                        \nThe reading of the machine will increase.<\/p>\n

                        Question 8.
                        \nA bomb explode in mid-air into two equal fragments. What is the relation between the direction of motion of the two fragments?
                        \nAnswer:
                        \nThe two fragments will fly off in exactly opposite directions.<\/p>\n

                        Question 9.
                        \nWhich law explains the following situation, Athlete runs a certain distance before long jump.
                        \nAnswer:
                        \nLaw of inertia which is Newton\u2019s first law of motion.<\/p>\n

                        \"Samacheer<\/p>\n

                        Question 10.
                        \nIs impulse a scalar?
                        \nAnswer:
                        \nNo, impulse is a vector quantity.<\/p>\n

                        Question 11.
                        \nWhen a lift moves with uniform velocity, what is its
                        \n(i) acceleration and
                        \n(ii) the apparent weight of the person standing inside the lift.
                        \nAnswer:
                        \n(i) Acceleration of the lift is zero.
                        \n(ii) The apparent weight of a person standing inside the lift is equal to his true weight since R = mg.<\/p>\n

                        Question 12.
                        \nWhen a lift falls freely, what happens to the apparent weight of a body in the lift.
                        \nAnswer:
                        \nThe apparent weight of the body in the lift is equal to zero. Since
                        \nR = m(g – g) = 0<\/p>\n

                        Question 13.
                        \nWhen a body falls freely it appears to have zero weight. Give reason.
                        \nAnswer:
                        \nWhen a body falls freely, it acts under the action of gravitational force alone. Hence it appears to have zero weight.<\/p>\n","protected":false},"excerpt":{"rendered":"

                        Students can download 10th Science Chapter 1 Laws of Motion Questions and Answers, Notes, Samacheer Kalvi 10th Science Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus, helps students complete homework assignments and to score high marks in board exams. Tamilnadu Samacheer Kalvi 10th Science Solutions Chapter 1 Laws of Motion …<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[2],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/posts\/1205"}],"collection":[{"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/comments?post=1205"}],"version-history":[{"count":1,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/posts\/1205\/revisions"}],"predecessor-version":[{"id":49348,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/posts\/1205\/revisions\/49348"}],"wp:attachment":[{"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/media?parent=1205"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/categories?post=1205"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/samacheer-kalvi.com\/wp-json\/wp\/v2\/tags?post=1205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}