Question

A $60kg$ man stands on a spring scale in the lift. At some instant he finds, scale reading has changed from $60kg$ to $50kg$ for a while and then comes back to the original mark. What should we conclude

• A. The lift was in constant motion upwards
• B. The lift was in constant motion downwards
• C. The lift while in constant motion upwards, is stopped suddenly
• D. The lift while in constant motion downwards, is suddenly stopped

Answer 1

The correct option is C The lift while in constant motion upwards, is stopped suddenly

reading on the spring scale basically denotes the normal reaction received by a person from the ground.In this case person will receive normal reaction($N$) in vertically upward direction and force of gravity($mg$) will be in downward direction.

Therefore,$N=50g;mg=60g$

Here, $mg-N=10g=+ve$

Therefore body will accelerate in downward direction.So, $C$ option is the correct