An electric motor is used to lift a crate onto the roof of a building.
The motor is supplied with 5000 J of energy. The crate has a mass of 20 kg and is lifted through a height of 15 m.
Gravitational field strength (ggg) = 10 N/kg
Calculate the energy transferred to the gravitational potential energy store of the crate.
Calculate the efficiency of the motor.
The motor becomes hot while it is lifting the crate.
Explain why.
The motor is switched off and cools down.
Describe what happens to the energy in the thermal store of the motor.
100 exam-style questions on Edexcel GCSE Physics 3.2 Dissipation and efficiency, covering 3.2.1 Dissipation of energy, 3.2.2 Reducing unwanted energy transfers, 3.2.3 Efficiency, and 3.2.4 Increasing efficiency. Each one has a worked solution and a mark scheme showing where the marks go.