1. The problem statement, all variables and given/known data (Irodov - Problems in General Physics - 1-31) 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? 2. Relevant equations Kinematic Equations, Conservation laws 3. The attempt at a solution I can solve this question if I can get one piece of information - the angle with the inclined plane with which the ball recoils. Using geometry I found that the incoming ball makes an angle 90+α with the plane. However I can't find the recoil angle. I suppose application of the conservation laws is required, but they bear no result for me - any clues on how to proceed?