Review Momentum and Impulse Past Paper Question

Which equation gives the momentum change of an object?

• momentum change = force x distance

• momentum change = force x time

Which expression can be used to determine the impulse on a tennis ball?

• force x time

• mass x initial velocity

• mass x acceleration

An object has a mass of 20 kg. Its velocity changes from 6 m/s to 10 m/s. Which impulse has acted on the object?

• 80 Ns

• 120 Ns

• 200 Ns

• 320 Ns

A sphere X collides head on with a second identical sphere Y which is stationary. The mass of each sphere is 0.15 kg. Sphere X is travelling at a velocity of 2.0 m/s before the collision and produces an impulse of 0.21 Ns on sphere Y. What is the velocity of sphere X after collision?

• 0.60 m/s in the opposite direction to Y

• 0.60 m/s in the same direction as Y

• 1.4 m/s in the opposite direction to Y

• 1.4 m/s in the same direction as Y

A resultant force F accelerates a car of mass m along a straight horizontal road from rest to a speed v in time t, giving it momentum p. Which pair of relationships for this situation is correct?

• pt = mv and F = pt

• p = mv and F = pt

• p = mv and Ft = p

• p = mvt and Ft = v

A car of mass 1200 kg is travelling along a straight horizontal road. Which impulse is needed to accelerate the car from 5.0 m/s to 10.0 m/s?

• 6000 Ns

• 12 000 Ns

• 15 000 Ns

• 18 000 Ns

A trolley of mass 4.0 kg travelling with a velocity of 4.0 m/s collides with a trolley of mass 2.0 kg travelling with a velocity of 2.0 m/s in the same direction. After the collision, the velocity of the 4.0 kg trolley is reduced to 3.0 m/s.

What is the velocity v of the 2.0 kg trolley after the collision?

• 0.25 m/s

• 4.0 m/s

• 5.0 m/s

• 16 m/s

A ball of mass m falls vertically and hits a hard surface. Its speed on hitting the surface is v₁. It rebounds vertically upwards with speed v₂. What is the change in momentum of the ball?

• mv₁

• mv₂

• m(v₁ + v₂)

• m(v₂ – v₁)

A gymnast jumps down from a high piece of apparatus. She gradually bends her knees as she lands. Which effect does this have?

• She will have a smaller change of momentum as she lands.

• She will lose less kinetic energy as she lands.

• She will exert a smaller impulse on the ground as she lands.

• She will experience a smaller force from the ground as she lands.

A small ball of mass 0.10 kg travels horizontally at a speed of 600 m s. It strikes a stationary wooden block of mass 1.9 kg resting on a frictionless horizontal surface. The ball stays in the block. What is the speed of the ball and the block immediately after the impact?

• 30 m/s

• 32 m/s

• 60 m/s

• 130 m/s