Describing Forces

Forces can have different effects; they can cause objects to start moving, stop moving, stay in the same place or rotate. They can also be of different types; gravitational forces are caused by and affect objects with mass, friction forces oppose relative motion and the force pushing up on you at the moment, the normal contact force, is due to compression of the material that you are sat on. In this context ‘normal’ means ‘at right angles to the surface’.

Forces also have things in common:

• all forces can be described as object A pulls/pushes object B
• all forces can be represented in both size and direction by an arrow on a diagram.

The first bullet point here is emphasising that all forces are caused by objects and they act on other objects.

Here are some examples.

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