An electric stage turntable rotates a piece of scenery. It is tested before and after a modification.
The table shows the energy transfers during each test.
| Energy transfer | Before modification in kJ\mathrm{kJ}kJ | After modification in kJ\mathrm{kJ}kJ |
|---|---|---|
| electrical energy supplied | 6.0 | 6.0 |
| transferred usefully to the kinetic energy store of the scenery | 4.1 | 4.8 |
| transferred to the thermal energy store of the machinery | 1.0 | 0.7 |
| transferred by sound | 0.3 | 0.2 |
The remaining energy is transferred to the thermal energy stores of the surroundings. There are no other energy transfers.
Calculate the decrease in energy transferred to the thermal energy stores of the surroundings after the modification.
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.