The energy of a system can be changed by work done by forces, electrically or by heating.
The Table shows three situations.
Table
| Situation | Way the energy of the system is changed |
|---|---|
| a pan of water on a hot cooker ring | |
| a crane lifting a load | |
| an electric drill connected to the mains |
Complete the Table.
A moving car brakes and comes to a stop.
Explain how the brakes change the energy stores of the system.
A student says:
'A person holding a heavy bag still is doing work on the bag.'
Explain whether the student is correct.