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 9 hp engine do in 2 seconds?

0 ft⋅lb | |

2 ft⋅lb | |

9900 ft⋅lb | |

18 ft⋅lb |