In physics, speed refers to the magnitude of the velocity of an object.
Speed is the total distance traveled divided by the time it takes to travel it.
Note that speed is a scalar, therefore it has no direction, and because it is a measure of magnitude, it is never negative.
Like velocity, units for its measurement are meters/second (m/s), and more commonly in informal circumstances kilometers/hour (kph) or (km/h) and miles/hour (mph) or (MPH).
- ↑ Serway and Beichner, Physics for Scientists and Engineers, Fifth Edition