Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!
Print

Science

How can we describe motion?

Page:

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  1. Next

The speed of a moving object can be calculated if the distance travelled and the time taken are known. The faster an object moves, the steeper is the line representing it on a distance-time graph.

The velocity of an object is its speed in a particular direction. In velocity-time graphs sloping lines represent steadily increasing or decreasing velocities. Horizontal lines represent movement at constant velocities.

Speed, distance and time

You should recall from your Key Stage 3 studies how to calculate the speed of an object from the distance travelled and the time taken.

The equation

When an object moves in a straight line at a steady speed, you can calculate its speed if you know how far it travels and how long it takes. This equation shows the relationship between speed, distance travelled and time taken:

Speed is distance divided by time taken.

For example, a car travels 300m in 20s.

Its speed is 300 ÷ 20 = 15m/s.

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

Page:

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  1. Next

Back to Explaining motion index

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.