Physics (AS & A Level) · Oct / Nov 2018 · Paper 12 · Question 10

The diagram shows two identical spheres X and Y. Initially, X moves with speed v directly towards Y. Y is stationary. The spheres collide elastically. What happens?

1. AX moves with speed 1/2 v to the right; Y moves with speed 1/2 v to the right
2. BX moves with speed v to the left; Y remains stationary
3. CX moves with speed 1/2 v to the left; Y moves with speed 1/2 v to the right
4. DX stops; Y moves with speed v to the right

As printed in the paper