KS3 Bitesize

We apologise for any problems you may be experiencing with our videos, for more information see the video information page.

Home > Science > Energy, electricity and forces > Forces

Science

Forces

Print
Back
Next

Unbalanced forces

When two forces acting on an object are not equal in size, we say that they are unbalanced forces.

If the forces on an object are unbalanced this is what happens:

  • an object that is not moving starts to move

  • an object that is moving changes speed or direction

There is a force of 100N behind a truck and a force of 60N in front of it. The force from behind the truck is greater than the force in front, so the truck speeds up in a forwards direction

Unbalanced forces make the truck speed up.

Resultant forces

The size of the overall force acting on an object is called the resultant force. If the forces are balanced, this is zero. In the example above, the resultant force is the difference between the two forces, which is 100 - 60 = 40 N.

Back
Next

More from Forces :

Activity Test
More from Energy, electricity and forces

Chat

Peiodic Table

posted by Huckleberry976

Activity

Forces activity

Something is pulling your mouse towards this link.

Play

Questionaut

Join Questionaut's quest to find his friend's hat.

Links

Learning Zone Broadband

More than 3000 video clips from BBC programmes.

bbc.co.uk navigation

BBC © 2013 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.