Physics (AS & A Level) · Feb / March 2020 · Paper 12 · Question 10

The diagram shows a particle P, travelling at speed v, about to collide with a stationary particle Q of the same mass. The collision is perfectly elastic. Which statement describes the motion of P and of Q immediately after the collision?

1. AP and Q both travel in the same direction with speed $\frac{1}{2}v$.
2. BP comes to rest and Q acquires speed $v$.
3. CP rebounds with speed $\frac{1}{2}v$ and Q acquires speed $\frac{1}{2}v$.
4. DP rebounds with speed $v$ and Q remains stationary.

As printed in the paper