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You've always wondered about the acceleration of the elevators in the 101 story-tall empire state building. one day, while visiting new york, you take your bathroom scale into the elevator and stand on them. the scales read 130 lb as the door closes. the reading varies between 110 lb and 160 lb as the elevator travels 101 floors. part a what is the magnitude of the acceleration as the elevator starts upward?

Respuesta :

Consider two stages of the travel in the elevator.

State 1: Before the elevator starts
The force exerted on the scale is 130 lb (your weight)

State 2: Elevator reaches maximum acceleration.
In addition to your weight, you acquire a force due to the acceleration of the elevator.
The additional inertial force (equal to the accelerating force) is exerted on the scale so that it reads 160 lb.

The inertial force is 160 - 130 = 30 lb.
Your mass is (130 lb)/(32 ft/s²) = 4.0625 poundals
The acceleration of the elevator is
a = Force/mass = (30 lb)/(4.0625 poundals) = 7.385 ft/s²

Answer:  7.385 ft/s²

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