A motor lifts a mass m vertically upward with constant speed v. If an additional constant downward resistive force f acts on the mass, the power delivered by the motor is:
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Question

A motor lifts a mass m vertically upward with constant speed v. If an additional constant downward resistive force f acts on the mass, the power delivered by the motor is:

G1 Physics · Accepted Answer

At constant speed the net force is zero, so motor force = mg+f. Hence motor power = (mg+f)v.