A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring…
A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads 49 $\mathrm{N}$, when the lift is stationary. If the lift moves downward with an acceleration of $5 \mathrm{~m} / \mathrm{s}^2$, the reading of the spring balance will be
$24 \mathrm{~N}$
$74 \mathrm{~N}$
$15 \mathrm{~N}$
$49 \mathrm{~N}$
Solution
Mass $=\frac{49}{9.8}=5 \mathrm{~kg}$. When lift is moving downward, apparent weight $=5(9.8-5)=5 \times 4.8=24 \mathrm{~N}$