A person stands on a scale inside an elevator at rest. The scale reads 700 N.

a) What is the persons mass?

b) The elevator accelerates upward momentarily at the rate of 1.5 m/s squared. What does the scale read then?

c) The elevator than moves with a steady (uniform) speed of 4 m/s. What does the scale read?

a) The mass of the person, m = 71.43 kg

b) The scale reading when elevator has an acceleration, W = 807.15 N

c) The scale reading when elevator has constant speed, W = 700 N

Explanation:

Given data,

The weight of the person inside the elevator, W = 700 N

The upward acceleration of elevator, a = 1.5 m/s²

The uniform speed of the elevator, v = 4 m/s

a) The mass of the person,

m = W / g

= 700 N / 9.8 m/s²

= 71.43 kg

b) The weight of the person,

W = mg + ma

= 700 N + 71.43 kg x 1.5 m/s²

= 807.15 N

c) When the speed is constant,

W = mg

= 700 N

The scale reading when the velocity is constant, W = 700 N