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.
InputMillimeters Per Second is the speed of an object covering a distance of one millimeter in a time of one second.
Miles Per Second is the speed of an object covering a distance of one mile in a time of one second.