A conveyor system is switched off after operating. Friction has increased the thermal energy store of one of its rollers.
The table shows the energy transfers involving the roller.
| Energy transfer | Energy transferred in J |
|---|---|
| to the thermal energy store of the roller while the conveyor operates | 84 |
| from the roller to the surrounding air while the roller cools | 31 |
| from the roller to the support frame while the roller cools | 26 |
Consider only the energy transfers shown in the table.
Calculate the energy remaining in the thermal energy store of the roller after it cools.
A student states, ‘The energy that leaves the roller while it cools no longer exists.’
Explain why the student's statement is incorrect and why this energy is unlikely to move the conveyor again.
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.