Summarizing Power

Summary

• Power is the rate at which work is done, or in equation form, for the average power \(P\) for work \(W\) done over a time \(t\), \(P=W/t\).
• The SI unit for power is the watt (W), where \(\text{1 W}=\text{1 J/s}\).
• The power of many devices such as electric motors is also often expressed in horsepower (hp), where \(\text{1 hp}=\text{746 W}\).

Glossary

power

the rate at which work is done

watt

(W) SI unit of power, with \(\text{1 W}=\text{1 J/s}\)

horsepower

an older non-SI unit of power, with \(\text{1 hp}=\text{746 W}\)

kilowatt-hour

\(\left(\text{kW}\cdot h\right)\) unit used primarily for electrical energy provided by electric utility companies