A particle $X$ is moving at speed $v$ and makes a perfectly elastic collision with an identical particle $Y$ that is at rest. After the collision, what are the speed and direction of motion of each particle?
- A$X$: stationary; $Y$: $v$ to the right
- B$X$: $\frac{v}{2}$ to the right; $Y$: $\frac{v}{2}$ to the right
- C$X$: $\frac{v}{2}$ to the left; $Y$: $\frac{v}{2}$ to the right
- D$X$: $v$ to the left; $Y$: stationary