An elevator motor is designed to raise a loaded elevator car of mass 917 kg at a

Question

An elevator motor is designed to raise a loaded elevator car of mass 917 kg at a speed of 1.96 m/s. Starting out, the elevator undergoes constant acceleration from rest to its design speed in 2.00 s. What is the minimum power that the elevator motor must be able to deliver to the car? Note: The instantaneous power being delivered by a force is the product of the force and the instantaneous speed. The force exerted by the elevator is greater during the car's acceleration than it is when the car is moving at constant speed. The minimum power which the motor must be able to deliver must be greater than the power required at any instant to accelerate the car from rest to its final speed and then continue to raise it at constant speed.

Choices

a) 1761 W

b) 15852 W

c) 19375 W

d) 17614 W

Explanation / Answer

acceleration = v/t = 1.96/2 = 0.98 m/s^2

maximum force = m(g+a) = 917*(9.8+0.98) = 9885 N

maximum power = Fv = 9885*1.96

= 19375 W

option c is correct.

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