The diagram depicts particle P moving at speed $v$ and just about to strike a stationary particle Q with the same mass. The collision is perfectly elastic. Which statement gives the motion of P and of Q immediately after the collision?
- AP rebounds with speed $\frac{1}{2}v$ and Q acquires speed $\frac{1}{2}v$.
- BP rebounds with speed $v$ and Q remains stationary.
- CP and Q both travel in the same direction with speed $\frac{1}{2}v$.
- DP comes to a standstill and Q acquires speed $v$.