Power is the rate at which work is done, **P = w/t**, or work per unit time. The **watt (W)** is the unit for power and is equal to 1 joule (or newton-meter) per second. **Horsepower (hp)** is another familiar unit of power used primarily for rating internal combustion engines. A 1 hp machine does 550 ft⋅lb of work in 1 second and 1 hp equals 746 watts.

How much work can a 5 hp engine do in 5 seconds?

13750 ft⋅lb | |

1 ft⋅lb | |

20 ft⋅lb | |

10 ft⋅lb |