Question

A body of mass $2\mathrm{kg}$ is suspended on a spring balance hung vertically in a lift. If the lift is falling downward under acceleration due to gravity g, then what will be the reading of the balance? If going upward with the same acceleration, then?

Answer 1

Step 1: Given data

A body of mass $2\mathrm{kg}$ is suspended on a spring balance hung vertically in a lift. If the lift is falling down under acceleration due to gravity g

Step 2: Finding the reading of the balance

Reading of the balance = apparent weight $W^{\text{'}}$ $=m(g+a)=m(g-g)=$ zero [here acceleration of lift $a=-g$ ]
If the lift is going upwards with the same acceleration $W^{\text{'}}=m(g+a)=m(g+g)=2mg=4kg$ [here acceleration of lift $a=+g$ ]