Question

The maximum separation between the floor of elevator and the ball during its flight would be

• A. 12 m
• B. 15 m
• C. 9.5 m
• D. 7.5 m

Answer 1

The correct option is C 9.5 m

The separation will be maximum when the ball comes to rest from initial release.
Using kinematics equation
$v^2=u^2+2aS$
Analyzing the motion of ball from elevator's non inertial reference frame.As the elevator is moving upwards with acceleration of $5m/s^2$, the pseudo force will be mass of ball times 5 m/s^2 in downwards direction.
the total downward acceleration is $g+5m/s^2$
$v=0,u=15m/s$
$0={15}^2-2\times 15S=7.5m$ from position of release
Total distance from floor$=2+7.5=9.5m$