Speed
is the rate at which an object moves. It is determined by measuring the
distance the object moves and the time that it takes to move that
distance. The speed is defined as the distance moved divided by the
elapsed time. Examples of the units are meters/second (meters per second)
and miles/hour (miles per hour or mph).During a trip, the speed can change. The total distance traveled divided by the total time elapsed is called the average speed. The speed at any particular time during the trip is called the instantaneous speed. A car's speedometer measures the instantaneous speed.
Another way to calculate the average speed for a trip is to calculate the average of all the instantaneous speeds during the trip.