Question

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

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

Answer 1

The correct option is D 24 N

Given,

$g=9.8m/s^2$

$a=5m/s^2$

When the lift is stationary, $mg=49N$

$m=\frac{49}{9.8}=5kg$

When lift moves downward then,

$F=m(g-a)$

$F=5(9.8-5)=24N$

The correct option is D.