What happens when the elevator is in free-fall, that is, what is the value for FN and what is the sensation experienced by the person in the elevator? Also, discuss the meaning of FN<0.

Weightlessness

Explanation:

When the elevator is in free fall, this can only occur when the cord of the elevator breaks.

The acceleration of the elevator will be equal to the acceleration due to gravity. That is:

a = g

Then, the body will experience what we called WEIGHTLESSNESS

Where the normal reaction N of the person will tend to zero. That is

N = 0

The value of FN < 0 because the person inside the lift will experience weightlessness.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.