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Vectors are quantities that have both size and direction.

Forces are vector quantities. That is they have both size and direction.

You can show the importance of the direction of a vector by the following simple experiment.

Get two strong men to pull on the ends of a rope (Figure 1). Now get a small child to push downwards on the centre of the rope (Figure 2).

It is quite easy to push the rope downwards because of the directions of all the forces. The men are pulling horizontally and when the rope is pushed down a little, only a very small fraction of their 'pull' is trying to prevent the rope from going downwards.

The further down the centre of the rope is pushed the harder it becomes to push it further. Can you explain why?

schoolphysics: Vectors and a rope animation

To see an animation of this experiment click on the animation link.

© Keith Gibbs 2011