Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. The scale reads 830 N for the first 3.6 s after the elevator starts moving, then 930 N for the next 3.6 s. What is the elevator's velocity 4.0 s after starting?

Explanation:

Given

Mass of Henry is 95 kg

Normal weight of Henry is

The scale reads the weight as 830 N for first 3.6 s i.e. less than the normal weight i.e. Elevator is moving downwards

Apparent weight is given by

After 3.6 s weight becomes 930 N which is approximately equal to normal weight. It implies elevator starts moving with constant velocity i.e. no acceleration.

If elevator starts from rest, it velocity after 3.6 s is

This velocity will remain continues as after 3.6 s, elevator starts moving with constant velocity.