Q. A $60-kg$ man stands on a spring scale in a lift. At some instant, he finds that the scale reading has changed from $60\, kg$ to $50\, kg$ for a while and then comes back to original mark. What should be concluded?
Laws of Motion
Solution:
The reading of the spring scale is the normal reaction between man and spring scale (see figure).
As the reading is decreasing, it means normal reaction is decreasing.
Firstly, the lift must be moving upwards with constant velocity and decelerated to rest.
