Question

A person stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.74 of the person's regular weight. Calculate the magnitude of acceleration of the elevator.
Is the direction of acceleration up or down?

Answer 1

Answer:

2.548 m/s^2, downwards

Explanation:

Let the true weight of the person is mg.

As the weight of the person decreases, so it means the the elevator is moving downward with an acceleration.

Reading of balance when it is accelerated down with an acceleration a is R = 0.74 times the weight of the person.

By use of Newton's second law

mg - R = ma

mg - 0.74 mg = m a

0.26 g = a

a = 0.26 x 9.8 = 2.548 m/s^2

Thus, the elevator is moving downwards with an acceleration 2.548 m/s^2 .