Question

A person with a mass of 85.0 kg is standing in a lift accelerating downwards at 0.450 m/s2. Draw a diagram showing the force acting on the person and calculate the force the person exerts on the floor of the lift.

Answer 1

The Newton's second law says

$$ma=mg-N$$

The weight of a person

$$P=N=m(g-a)=85.0(9.81-0.450)=796\:\rm N$$