Power is the rate at which energy is transferred, or the rate at which work is done. It is measured in watts, W. A power of 1 watt means an energy transfer of 1 joule per second.
The equations are P = E ÷ t and P = W ÷ t, where P is power in watts, E is energy transferred in joules, W is work done in joules and t is time in seconds.
For example, a motor that does 600 J of work in 12 s has a power of 600 ÷ 12 = 50 W. A kettle that transfers 360000 J of energy in 180 s has a power of 360000 ÷ 180 = 2000 W, so it transfers 2000 joules every second.
Two electric motors can lift the same weight through the same height. They do the same amount of work, but the motor that takes less time has the greater power because it transfers energy faster.