Defining Power
- The power of a machine is the rate at which it transfers energy
- Since work done is equal to the energy transferred, power can also be defined as the rate of doing work or the work done per unit time
- Where:
- P = power in watts (W)
- E = energy in joules (J)
- W = work done in joules (J) or newton metres (N m)
- t = time in seconds (s)
- You may be familiar with labels on lightbulbs which indicate their power such as 60 W or 100 W
- These power ratings tell you about energy transferred electrically rather than mechanically and so will require a different equation