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

Options

A. 49 N
B. 24 N
C. 74 N
D. 15 N

Answer

b

Explanation

Here, reaction of floor is `R = m(g-a)`
When the lift is stationary, then `49 = m xx 9.8` or `m= 5 kg`
Hence `R = 5(9.8 - 5) = 24 N`
Hence choice is (b).