A freight elevator of mass is raised vertically through in by an electric motor
PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A freight elevator of mass 500kg is raised vertically through 18m in 25s by an electric motor. During the motion the elevator experiences a constant frictional resistance of 800N. Take g=9.8m/s2.
(i) Calculate the total upward force that the motor must exert on the elevator.
(ii) Determine the work done by the motor in raising the elevator through the given height.
(iii) Compute the average power developed by the motor.
(iv) If the elevator is to be raised through the same height in 15s under the same frictional conditions, calculate the power that the motor must now supply and state how many times larger it is than the power found in part (iii).