Force and Laws of Motion : NCERT Exemplar

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Multiple Choice Questions : 

Q.1 Which of the following statement is not correct for an object moving along a straight path in an accelerated motion?

(a) Its speed keeps changing

(b) Its velocity always changes

(c) It always goes away from the earth

(d) A force is always acting on it

Sol. (c)

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Q.2 According to the third law of motion, action and reaction

(a) Always act on the same body

(b) Always act on different bodies in opposite directions

(c) Have same magnitude and directions

(d) Act on either body at normal to each other

Sol. (b)

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Q.3 A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goal keeper to

(a) Exert larger force on the ball

(b) Reduce the force exerted by the ball on hands

(c) Increase the rate of change of momentum

(d) Decrease the rate of change of momentum

Sol. (b)

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Q.4 The inertia of an object tends to cause the object

(a) To increase its speed

(b) To decrease its speed

(c) To resist any change in its state of motion

(d) To decelerate due to friction

Sol. (c)

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Q.5 A passenger in a moving train tosses a coin which falls behind him. It means that motion of the train is

(a) Accelerated

(b) Uniform

(c) Retarded

(d) Along circular tracks

Sol. (a)

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Q.6 An object of mass 2 kg is sliding with a constant velocity of 4 m s–1 on a friction less horizontal table. The force required to keep the object moving with the same velocity is

(a) 32 N

(b) 0 N

(c) 2 N

(d) 8 N

Sol. (b)

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Q.7 Rocket works on the principle of conservation of

(a) Mass

(b) Energy

(c) Momentum

(d) Velocity

Sol. (c)

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Q.8 A water tanker filled up to 2 3 of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would

(a) Move backward

(b) Move forward

(c) Be unaffected

(d) Rise upwards

Sol. (b)