A motor drives a conveyor belt. During one complete operation, the motor runs at setting 1 and then at setting 2. The table shows the power supplied to the motor, the useful power transferred to the kinetic energy store of the belt, and the operating time for each setting.
| Setting | Input power in kW\mathrm{kW}kW | Useful output power in kW\mathrm{kW}kW | Operating time in s\mathrm{s}s |
|---|---|---|---|
| 1 | 1.50 | 0.90 | 40 |
| 2 | 1.00 | 0.80 | 100 |
Use: energy transferred in kJ=power in kW×time in s\text{energy transferred in kJ}=\text{power in kW}\times\text{time in s}energy transferred in kJ=power in kW×time in s
Calculate the efficiency of the motor over the complete operation.
Explain what happens to the energy supplied to the motor that is not transferred to the kinetic energy store of the belt.
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.