# 3 | Speed

## Speed

• Speed is a measure of how fast something moves.
• It can be measured as average speed or as instantaneous speed.
• Average speed is an overall measurement of speed between two points in time, but doesn’t indicate how the speed may have varied during that time.
• For example, average speed can be calculated for a road trip, which is based on departure time, arrival time and the distance travelled, but does not indicate how the car’s speed increased or decreased or whether the car made any stops during that time.
• Instantaneous speed is a measure of speed at a particular point in time.
• For example, the speed shown on a car’s speedometer is a measure of instantaneous speed – it shows how fast the car is moving at that point in time. The reading on a speedometer will change constantly during a car’s journey, reflecting the changes in speed.

Average speed is an overall measurement of speed between two points in time.
Instantaneous speed is a measure of speed at a particular point in time.