Question

A ball is thrown vertically upward with a velocity u frif the top of the tower .if it strikes the ground with a velocity 3u the time taken by the ball to reach the ground is and in terms of u is required

Answer 1

initial velocity = u =-u
final velocity = v = 3u
acceleration due to gravity = g
v = u + gt
3u = -u + gt
3u+u/g = t
4u/g = t