A diver stands on the end of a springboard. The board is bent downwards and the diver is momentarily at rest. The board then straightens and launches the diver upwards.
The table shows the changes in energy stores between the instant the board starts to straighten and a later instant when the diver is moving upwards above the board.
| Energy store | Change in energy in J\text{J}J |
|---|---|
| elastic store of the springboard | decrease of 1800 |
| gravitational potential energy store of the diver | increase of 1200 |
| kinetic store of the diver | increase of 250 |
| thermal stores of the springboard, diver and nearby air | increase not shown |
Gravitational field strength (ggg) = 10 N/kg
Calculate the increase in the thermal stores of the springboard, diver and nearby air.
The diver has a mass of 60 kg.
Calculate how far the diver rises vertically between the two instants.
State the energy transfer pathway while the springboard pushes the diver upwards.
The diver, springboard, Earth and nearby air are treated as a closed system.
Explain why energy transferred to the nearby air does not cause the total energy of this system to decrease.