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

Options

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

Answer

C

Explanation

When the lift is moving down with an acceleration 'a', the apparent weight of the ball = mg - ma.
`therefore ` the man in the lift will feel the apparent acceleration of the ball `=(g-a)`.
The man inside the lift is in a non vertical frame.
But for a man standing outside the lift, the acceleration of the ball will be g. He is in an inertial frame.