On a building site is 600 W. Electric winch and a pulley were used to lift bricks from the ground. The winch raised a load of 500 N through a height of 3 m in 25s. During this time, the average power supplied to the winch was 600 W.
Calculate how much useful energy was transferred by the motor.
Calculate the percentage efficiency of the system.
Explain why the efficiency of a winch can never be as much as 100%