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 modal downwards
• C. The lift while in constant motion upwards, is stopped suddenly
• D. The lift while in constant motto downwards, is suddenly stopped

Answer 1

Answer: (C)

For upward acceleration apparent weight
$=m(g+a)$
If lift suddenly stops during upward motion then apparent weight $=m(g-a)$ because instead of acceleration, we will consider retardation.
In the problem it is given that scale reading initially was $60kg$ and due to sudden jerk reading decreases and finally comes back to the original mark ie, $60kg$.
So, we can conclude that lift was moving upwards with constant speed and suddenly stops.