Question

A ball starts falling with zero initial velocity on a smooth inclined plane forming an angle alpha with the horizontal. Having fallen 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?
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Answer 1

The ball strikes the inclined plane (Ox) at point O (origin) with velocity vo= √2gh ...(1) As the ball elastically rebounds, it recalls with same velocity vo, 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.

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