P3 Revision (Speed)
You can calculate average speed using the equation: speed = distance ÷ time. Average speed cameras are used to find out if a motorist is driving too quickly. A distance-time graph shows how the distance of an object changes over time, and its speed.
Average speed = distance ÷ time
For example, what is the average speed of a runner who covers 100 m in 10 s?
Average speed = 100 ÷ 10 = 10 m/s
In science, average speed is usually given in metres per second, m/s. If you are given the distance in km, multiply it by 1000 to get the distance in m.
For example, a car covers 2 km in 100 s. What is its average speed?
2 km = 2 × 1000 = 2000 m
Average speed = 2000 ÷ 100 = 20 m/s