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2. A car has a mass of 400 kg. The car is on a scale, which is on a freight elev

ID: 2303567 • Letter: 2

Question

2. A car has a mass of 400 kg. The car is on a scale, which is on a freight elevator. For each situation, what will be the reading on the scale in kN? a. The elevator is moving upward with a constant velocity of 8 m/s. g b. The elevator is moving downward at 8 m/s and accelerating at 0.5 g. The elevator is moving upward at 8 m/s and accelerating at 0.5 g. The elevator is moving downward at 8 m/s and decelerating at 0.5 g. The elevator is moving upward at 8 m/s and decelerating at 0.5 g. c. d. scale e.

Explanation / Answer

A)

when the elevator is moving with constant velocity a = 0

reading R = 400*9.8= 3.92 KN

B)

accelerating at 0.5g

reading R = mg-ma

= 400*9.8-400*0.5*9.8

= 1.96 KN

C)

elevator is moving upward at 0.5 g

reading R = mg+ma

= 400*9.8+400*0.5*9.8

= 5.88 KN

d)

decelerating a = -0.5g

reading R = mg-ma

= 400*9.8+400*0.5*9.8

= 5.88 KN

e)

Deccelerating a = 0.5g

reading R = mg+ma

= 400*9.8-400*0.5*9.8

= 1.96KN