2.3 Speed

Speed is the amount of distance traveled in a certain amount of time. The U.S. unit is mph (miles per hour), the SI unit is km/h (kilometer per hour). One mile is about 1.6 km. In science, however, it is more common to measure speed by meter per second, or $\mathrm{m}\mathrm{s}^{-1}$.

The physics symbol for speed (velocity) is ``v''.