### Mechanics

# Ball and Wall

Problem by zainul abidin

30 Nov 1999 00:00 WIB

A ball is thrown from the floor at an initial velocity $v_0$ and at an angle $\alpha$ to the horizontal floor. A vertical wall is located at a distance $d$ from the point where the ball was thrown. Assuming all collisions are elastic and friction can be ignored, determine the condition for the angle $\alpha$ and the initial velocity $v_0$, such that the ball returns to the point from which it was thrown.