A parachutist of mass 75 kg falls through the air. The table shows measurements at two points, P and Q.
| Point | Height above the ground in m\mathrm{m}m | Speed in m/s\mathrm{m/s}m/s |
|---|---|---|
| P | 1200 | 20 |
| Q | 800 | 40 |
Later, at a lower point R, the speed of the parachutist has decreased to 10 m/s.
Use g=10 N/kgg=10\ \mathrm{N/kg}g=10 N/kg.
Calculate the energy transferred to the surroundings as the parachutist falls from P to Q.
Explain why the energy transferred to the surroundings from Q to R is greater than the decrease in the gravitational store of the parachutist between these points.