`P` and `Q` are two identical masses at rest suspended by an inextensible string passing over a smooth frictionless pulley. Mass `P` is given a downward push with a speed `v` as shown in Fig. It collides elastically with the floor and rebounds immediately. What happens immediately after collision?

Options

A. `P` and `Q` both move upwards with equal speeds.
B. `P` and `Q` both move upwards with different speeds
C. `P` moves upwards and `Q` moves downwards with equal speeds.
D. Both `P` and `Q` are at rest.

Answer

A

Explanation

Since collision is elastic, `P` will rebound with same velocity as it stirkes with. And at the time of collision, velocities of `P` and `Q` will be same in magnitude.