A firework burns in a closed system that includes the firework, its gases and the surroundings. No energy is transferred across the system boundary.
The table shows two energy stores at the start and at a later instant while the firework is still burning.
| Energy store | At the start | At the later instant |
|---|---|---|
| chemical energy store of the firework powder | 3000 J | 600 J |
| kinetic energy store of the gases | 0 J | 550 J |
The only other store that changes is the thermal energy store of the gases and surroundings.
Calculate the increase in the thermal energy store of the gases and surroundings between the start and the later instant. State whether the total energy of the system changes, and give a reason for your answer.