Question

An open elevator is ascending with zero
acceleration. The speed v = 10 m/s. A ball is thrown vertically up
by a boy when he is at a height h = 10 m from the ground. The
velocity of projection is v = 30 m/s with respect to elevator. Find
(i) the maximum height attained by the ball.
(ii) the time taken by the ball to meet the elevator again.
(iii) time taken by the ball to reach the ground after crossing the
elevator.​

Answer 1

Answer:

(A) Absolute velocity of ball = 40 m/s (upwards) h = 90 m (B) Maximum height from left = (30)2 / 2 x 10 = 45 m (C) The ball unless meet the elevator again when displacement of ball = displacement of lift (D) Let t0 be the total time taken by the ball to reach the ground then - 10 = 40 x to - 1/2 x 10 x to2 ⇒ t0 = 8.24 s. ∴ time taken by the ball for each the ground after crossing the elevator = t0 – t = 2.24 s.