1) mass is defined density x cross sectional area x speed a) Correct b) Incorrect 2) A body that is stationary remains stationary if there is no external force acting on it a) Correct b) Incorrect 3) total KE of a system remains unchanged in elastic collisions only a) Correct b) Incorrect 4) total momentum of a system remains unchanged in elastic collisions only a) Correct b) Incorrect 5) When a body falls in air, its velocity increases at a decreasing rate a) Correct b) Incorrect 6) momentum is defined as mass x speed a) Correct b) Incorrect 7) A man in a lift feels himself heavier when the lift accelerates upwards a) Correct b) Incorrect 8) in an inelastic collision, total final KE < total initial KE of the system a) Correct b) Incorrect 9) A bus is at rest then it moves forwards suddenly, passengers in the bus move backwards a) Correct b) Incorrect 10) When two bodies move together after a collision, the relative speed of separation = 0 a) Correct b) Incorrect 11) Action and reaction have equal magnitude but in opposite direction regardless the motion of two bodies a) Correct b) Incorrect 12) Force is defined as the change in momentum per unit time a) Correct b) Incorrect 13) Force is defined as mass x acceleration a) Correct b) Incorrect 14) A bus is moving then it stops suddenly, passengers in the bus move backwards a) Correct b) Incorrect 15) When a body falls in air, its displacement is constant a) Correct b) Incorrect 16) Action and reaction have equal magnitude when only two bodies move with a constant velocity a) Correct b) Incorrect 17) the mass of a body varies but its weight is fixed a) Correct b) Incorrect 18) A body with large mass has a low resistance to any change in motion. a) Correct b) Incorrect 19) total energy of a system is not conserved in inelastic collisions a) Correct b) Incorrect 20) Force, acceleration and velocity are always in the same direction a) Correct b) Incorrect 21) when air resistance balances the weight of a body, the body moves with a constant velocity a) Correct b) Incorrect 22) total momentum of a system remains unchanged if there is no external force a) Correct b) Incorrect 23) The area under the graph of force vs time represents the change in momentum a) Correct b) Incorrect 24) A man in a lift feels himself heavier when the lift accelerates downwards a) Correct b) Incorrect 25) Forces always come in pairs a) Correct b) Incorrect 26) Action and reaction cancel out each other. a) Correct b) Incorrect 27) No friction acts on a box that is rest on a flat table a) Correct b) Incorrect 28) No friction acts on a box that is rest on a ramp a) Correct b) Incorrect 29) When a ball hits the ground and bounces upwards, normal contact force > its weight a) Correct b) Incorrect 30) Air resistance increases with the velocity of a moving body a) Correct b) Incorrect 31) When two bodies move apart after a collision, the relative speed of separation = 0 a) Correct b) Incorrect 32) When a small car hits a big truck, the acceleration of the truck is smaller. a) Correct b) Incorrect 33) When a ball hits the ground and bounces upwards, normal contact force balances its weight a) Correct b) Incorrect 34) When a constant net force acts on a body, its velocity increases uniformly a) Correct b) Incorrect 35) When a constant net force acts on a body, its acceleration increases uniformly a) Correct b) Incorrect 36) In an explosion, total KE of a system is not conserved a) Correct b) Incorrect 37) When A moves towards B which is at rest, the relative speed of approach is larger than that when A and B approach each other a) Correct b) Incorrect 38) In an explosion, total momentum of a system is zero a) correct b) incorrect

Chap 3 Dynamics

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