Question

A lift is moving down with acceleration $a$. A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively.

• A. $g,g$
• B. $g-a,g-a$
• C. $g-a,g$
• D. $a,g$

Answer 1

The correct option is C $g-a,g$

Lift is accelerating downwards, so acceleration of lift w.r.t. ground $a_{lg}=a$

Acceleration of ball w.r.t. ground $a_{bg}=g$

Acceleration of ball w.r.t. lift $a_{bl}=a_{bg}-a_{lg}=g-a$