# What is *speed*?

**Speed**is a measure of how fast something is moving. The average speed of an object in a certain time is the distance the object travelled divided by the time. Speed is often confused with

*velocity*.

**Velocity**is speed with a direction. In other words, velocity is the vector quantity and speed is the scalar quantity.

## Input

**Millimeters Per Second**is the speed of an object covering a distance of one millimeter in a time of one second.

## Output

**Knot**is a unit of speed equal to one nautical mile per hour or exactly 1.852 km/h.