A 1000 kg elevator is lifted vertically at a constant speed of 2 m/s by a cable. What is the power delivered by the motor to lift the elevator?

Core Concept

The power delivered by the motor is P = F × v, where F is the force required to lift the elevator and v is the velocity. Since the elevator is moving at constant speed, the net force is zero, so the tension in the cable equals the weight of the elevator: F = mg = 1000 kg × 9.8 m/s² = 9800 N. The power is then P = 9800 N × 2 m/s = 19600 W, which corresponds to option D.