A 950 kg sack of cement is lifted to the top of a building 50 m high by an electric motor.
a Calculate the increase in the gravitational potential energy of the sack of cement.
b The output power of the motor is 4.0 kW. Calculate how long it took to raise the sack to the top
of the building.
c The electrical power transferred by the motor is 6.9 kW. In raising the sack to the top of the building,
how much energy is wasted in the motor as heat?
