Power is the rate of doing work. Power is measured in watts (W). An object has a higher power if it does more work in a certain time, or if it takes less time to do a certain amount of work.
2
| Person | Force (N) | Distance moved (m) | Work done (J) |
| Alice | 50 | 3 | 150 |
| Bernard | 10 | 10 | 100 |
| Courtney | 200 | 1 | 200 |
| Dionne | 500 | 0.3 | 150 |
| Edward | 75 | 2 | 150 |
3 Lowest power Bernard (10 W)
Alice (15 W)
Courtney (20 W)
Edward (25 W)
Dionne (30 W)
1 70 x 9.8 x 5 = 3430 J
2 3430/7 = 490 W
3 The work done on each flight of stairs is the same as the one before.
4 The time taken to climb each flight of stairs is longer than the one before.
5 (Exact figures may vary slightly depending on whether pupils calculate each time separately from work/power or calculate the increase from the previous time directly.)
| Flight of stairs | Work done in climbing flight (J) | Power (W) (to 1 d.p.) | Time to climb flight (s) (to 1 d.p.) |
| 1 | 3430 | 490.0 | 7.0 |
| 2 | 3430 | 465.5 | 7.4 |
| 3 | 3430 | 442.2 | 7.8 |
| 4 | 3430 | 420.1 | 8.2 |
| 5 | 3430 | 399.1 | 8.6 |
| 6 | 3430 | 379.2 | 9.0 |
| 7 | 3430 | 360.2 | 9.5 |
| 8 | 3430 | 342.2 | 10.0 |
6 Work = 3430 x 8 = 27 440 J, time = 67.5 s, Power = 406.5 W (to 1 d.p.)
