During a firework display, the firework and its surroundings are treated as a closed system. All changes during the burn are accounted for by the three rows in the table.
| Energy store | Initial energy | Final energy |
|---|---|---|
| Chemical | 700 J | 400 J |
| Kinetic | 150 J | 300 J |
| Thermal | XXX | 550 J |
Which value is XXX, the initial energy in the thermal store?
400 J400\ \mathrm{J}400 J
700 J700\ \mathrm{J}700 J
850 J850\ \mathrm{J}850 J
550 J550\ \mathrm{J}550 J
115 exam-style questions on Edexcel GCSE Physics 8.1 Energy transfers and work, covering 8.1.1 Energy stores and transfer diagrams, 8.1.2 Ways of changing a system's energy, and 8.1.3 Work done by forces. Each one has a worked solution and a mark scheme showing where the marks go.