Let acceleration of ball =ab​ and acceleration of man is =am​ With respect to the man standing in the lift, the acceleration of the ball abm​=ab​−am​⇒abm​=g−a Where a is the acceleration of the man as the acceleration of the lift is a. With respect to the man standing on the ground the acceleration of the ball abm​=ab​−am​⇒abm​=g−0=g