An electric motor rotates a mixing drum through a gearbox. During one start-up, the motor is supplied with 2.40 kJ of energy, and the drum gains 1.224 kJ in its kinetic energy store.
The gearbox is 85% efficient. The useful energy transferred by the motor is the energy supplied to the gearbox.
Calculate the efficiency 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.