Q. A ball is dropped vertically from a height d above the ground. It hits the ground and bounces up vertically to a height d/2 . Neglecting subsequent motion and air resistance, its velocity v varies with height h above the ground as:
Sol: When ball is falling down from height d and reaches at height h , then velocity acquired by the ball is
v2= 2g(d-h) —(i)
This is downward velocity and is taken as negative .
When h = d , v = 0
When h =0 , v2 = (2 g d)
Hence from eqn(i) , the variation of v & h is parabolic below h axis