Two steel balls fall freely on an elastic slab. The first ball is dropped from a height `h_(1)` and the second from a height `h_(2)(h_(2) lt h_(1)) sec` after the first ball. After the passage of time T, the velocities of the balls coincide in magnitude and direction. Determine the time T and the time interval during which the velocities of the two balls will be equal assuming that the balls do not collide.

Answer

`[(2sqrt(2)(sqrt(h_(1))-sqrt(h_(2))))/(sqrt(g))]`