1. A 56.1-kg student is entering an elevator on the 2nd floor of the library and

Question

1. A 56.1-kg student is entering an elevator on the 2nd floor of the library and steps on a bathroom scale that happens to be there. The student pushes the button to the 5th floor; the doors close and the elevator begins to speed up at a constant rate of 0.526 m/s^2. While the elevator speeds up, what is the reading of the scale? Convert your answer to pounds and use lbs as units

2.You are standing on a scale inside an elevator. The scale reads 127 percent of your weight. What is the acceleration of the elevator?

(Define positive y upward.)

Explanation / Answer

1.

When elevator is speeding up,
Net reaction force = m*g+m*a
= m*(g+a)
= 56.1*(9.8 + 0.526)
= 579.29 N
= 130.23 lbs

scale will read this
Answer: 130.23 lbs

2.
Since reaction is more than weight, elevator is going up
Net reaction force = 1.27*mg
1.27 = m*g+m*a
m*a = 0.27*mg
a = 0.27*g
=2.65 m/s^2
Answer: 2.65 m/s^2

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