Question

A ball is moving with velocity `2m//s` towards a heavy wall moving towards the ball with speed `1m//s` as shown in figure. Assuming collision to be elastic, find the velocity of ball immediately after the collision.

Answer 1

The speed of wall will not change after the collision. So, let v be the velocity of the ball after collision in the direction shown in figure, Since, collision is elastic (e=1),

separation speed = approach speed
or `v-1 = 2+1 or v = ms^(-1)`