# What are forces?

• A force is a push or pull that causes a change in speed, direction or shape.

• Some forces are affected by speed, other forces are not.

• All forces come in pairs, no force exists by itself.

## Examples of forces

Important forces include: gravity, electromagnetism and friction.

## Where do forces come from?

Forces can be made in a number of different ways. They can be created when two objects press against each other, but are also present when objects aren't even touching!

Examples of forces acting without objects touching include gravity pulling you down to the ground when you jump in the air, or a magnet lifting a paperclip off the table.

## Do forces change with speed?

It depends on the force. Some forces are the same whether or not you are moving. Gravity, for example, will pull you down whether you are moving or not.

Air resistance is a force that tries to slow us down; the faster we go, the more air resistance we feel. Therefore air resistance, unlike gravity, is affected by speed.

## Forces come in pairs

No force exists by itself. Every action has an equal and opposite reaction. If you push on something (action) it pushes back (reaction).

With a racing car the wheel tries to push the road backwards (action) and in return the road pushes the wheel and the car forwards (reaction).

## When is it useful to know about forces?

It is crucial to know about forces when designing and driving racing cars. To accelerate quickly and travel at high speeds, racing cars need to have as little air resistance as possible. The shape of the cars is important in reducing air resistance.

## Forces quiz

Found out how much you know with this quick science quiz.