Question

A ball starts falling with zero initial velocity on a smooth inclined plane forming an angle α with the horizontal. Having fallen the distance h, the ball rebounds elastically off the inclined plane. At what distance from the impact point will the -ball rebound for the second time?

Answer 1

The ball strikes the inclined plane (Ox) at point O (origin) with velocity v_o= √2gh ...(1)

As the ball elastically rebounds, it recalls with same velocity v_o, at the same angle α from the normal or y-axis (Fig.). Let the ball strikes the inclined second time at P, which is at a distance l(say) from the point O, along the incline. From the equation

Hence the sought distance,