What is Power?
What is Power?
Power—the word conjures up many images: a professional football player muscling aside his opponent, a dragster roaring away from the starting line, a volcano blowing its lava into the atmosphere, or a rocket blasting off, as in the figure below.
This powerful rocket on the Space Shuttle Endeavor did work and consumed energy at a very high rate. (credit: NASA)
These images of power have in common the rapid performance of work, consistent with the scientific definition of power (\(P\)) as the rate at which work is done.
Power
Power is the rate at which work is done.
\(P=\cfrac{W}{t}\)
The SI unit for power is the watt (\(W\)), where 1 watt equals 1 joule/second \(\left(\text{1 W}=1\text{ J/s}\right)\text{.}\)
Because work is energy transfer, power is also the rate at which energy is expended. A 60-W light bulb, for example, expends 60 J of energy per second. Great power means a large amount of work or energy developed in a short time. For example, when a powerful car accelerates rapidly, it does a large amount of work and consumes a large amount of fuel in a short time.
This lesson is part of:
Work, Energy and Energy Resources