A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49N, when the lift is stationary. If the lift moves downward with an acceleration of `5m//2^2`, the reading of the spring balance will be

Explanation

When the elevator is stationary,
Then, w=mg
`implies 49=mxx9.8`
`implies m=(49)/(9.8)=5`
When the elevator is moving downward with an acceleration
R=m(9.8-a)=5(9.8-5)=24N