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:
= 3.6 km.h-1
1 mph = 1.609 km.h-1
1 knot = 1.852 km.h-1 = 0.514 m.s-1.
Mach 1 = ca. 1200 km.h-1 = ca. 330 m.s-1;