Understanding Collisions

(a) State two quantities that are conserved in an elastic collision.

State what is meant by:

(ii) A completely inelastic collision.

State what is meant by a perfectly elastic collision.

b An arrow of mass $0.25 \mathrm{kg}$ is fired horizontally towards an apple of mass $0.10 \mathrm{kg}$ that is hanging on a string, as shown in Figure. The horizontal velocity of the arrow as it enters the apple is $30 \mathrm{m}{ \mathrm{s}}^{-1}$. The apple was initially at rest and the arrow sticks in the apple.

(iv) A rubber-tipped arrow of mass $0.25 \mathrm{kg}$ is fired at the centre of a stationary ball of mass $0.25 \mathrm{kg}$. The collision is perfectly elastic. Describe what happens and state the relative speed of separation of the arrow and the ball.

 Explain whether or not momentum is conserved in the situation described in part b.

A snooker ball of mass $0.35 \mathrm{kg}$ hits the side of a snooker table at right angles and bounces off also at right angles. Its speed before collision is $2.8 \mathrm{m}{ \mathrm{s}}^{-1}$ and its speed after is $2.5 \mathrm{m}{\mathrm{s}}^{-1}$. Calculate the change in the momentum of the ball.

(a) Explain what is meant by an:

(ii) Inelastic collision

(a) Explain what is meant by an:

(i) Elastic collision

Copy this table, choosing the correct words from each pair.