Power

Power, by its definition, is the rate at which work is done or the rate at which energy is transferred.

or

The SI unit for power is joules per second, which is called a Watt. (The British system uses foot-pounds per second.) Horsepower is another common way to measure power. Horsepower is usually used when measuring the power of huge engines and for other similar purposes. Conversion factors are:

Alternately, since velocity is distance per unit time, power may also be expressed as:

If two machines have different power ratings, both may be able to do the same mount of work, but the one with a higher rating will be able to do that work faster.

For some additional studies on the topic, you can click on the website listed below:

http://www.physicsclassroom.com/Class/energy/u5l1e.html