Relative motion

Let us consider the upward direction to be positive

Initial velocity of the ball (u) = 49 m s-1

The speed of the ball will be the same when it reaches the boy's hand's but will be moving in a downward direction. Therefore final velocity (v) = -49 m s-1

Acceleration (a) = -9.8 m s-2

Using the first equation of motion we have

In the second case, as the ball has been thrown after the lift has started moving upwards with a constant velocity, the relative velocity of the ball with respect to the boy remains the same and therefore the ball will again take 10 seconds to reach the boy's hands.