Speed
Speed is the rate of motion expressed as distance moved per unit time. Speed is a scalar; the equivalent vector quantity is known as velocity.
Units of speed include:
- metre per second (symbol m.s-1), the SI derived unit
- kilometre per hour, km.h-1
- mile per hour
- knot (nautical miles per hour)
- Mach, where Mach 1 is the speed of sound; Mach n is n times as fast.
Speed is also:
- slang for amphetamines
- an American film: see Speed (movie).
