A body is projected upwards with a velocity u. It passes through a certain point above the ground after t1. The time after which the body passes through the same point during the return journey is

Suppose v be the velocity attained by the body after time t1.Then v=u−gt1 …..(i)Let the body reach the same point at time t2. Now velocity will be downwards with same magnitude v. Then−v=u−gt2                             ......(ii) (i) −(ii)⇒2v=gt2−t1 or  t2−t1=2vg=2gu−gt1=2ug−t1