Speed

For alternate uses, see Speed (disambiguation).

Speed is the rate of motion expressed as distance moved per unit of time. Speed is a scalar quantity; the equivalent vector quantity is known as velocity.

Units of speed include:

meter per second, (symbol m/s), the SI derived unit
kilometer per hour, (symbol km/h)
mile per hour, (symbol mph)
knot (nautical miles per hour)
Mach, where Mach 1 is the speed of sound; Mach n is n times as fast.

1 m/s = 3.6 km/h

1 mph = 1.609 km/h

1 knot = 1.852 km/h = 0.514 m/s

Mach 1 = about 1200 km/h = about 330 m/s