speed

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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

The speed of an object tells you how fast or slow it is moving. You can find the average speed of an object if you know:

  • The distance travelled
  • The time taken to travel that distance

You can calculate average speed using the equation:

Speed = distance ÷ time

Distance-time graphs represent how an object moves. They show how the distance moved from a starting point changes over time.

Calculating average speed

This equation shows the relationship between average speed, distance and time:

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

Check your understanding of this topic by having a go at this activity:

Average speed cameras

Speed cameras are used to find out if a motorist is speeding. The camera takes two photographs of the vehicle…

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