Question

An object is hung from a spring balance attached to the ceiling of an elevator cab. The balance reads 85 N when the elevator is standing still.

a) What is the reading when the elevator is moving upward with a constant speed of 7.9 m/s?

b) What is the reading when the elevator is moving upward with a speed of 7.9 m/s while decelerating at a rate of 1.1 m/s2?

Answer 1

Step-by-step explanation:

Balance force ( W ) = 85 N

a) moving upward with constant velocity (V ) = 7.9 m/s.

The reading will not change since it is moving with constant velocity

W = 85 N

b) Moving upward with V = 7.9 m/s and decelerating at the rate of (a ) = 1.1 m /s²

The net force ( F ) = W - ma

where m = W/g = 85/9.81 = 8.6646 kg

F = 85 - 8.6646 * 1.1 = 75.4689 N