In kinematics, the
speed of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The
average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the
instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Speed is the magnitude of
velocity, which indicates additionally the direction of motion.