Words to learn

friction - grip - smooth - rough

Friction is a force that acts when two surfaces rub together. Some materials cause more friction than others.
Rub your hands together. Feel them rubbing and getting warm.

When hands are rubbed together acts between them

Friction can start and stop things moving. You need the friction between the floor and your shoes to help you start walking.

You can go very fast down a slide. There will be friction between your clothes and the surface of the slide

There is friction between the bottom of your shoes and the floor which helps your shoes to grip the floor surface. This stops you from sliding.

Ice is slippery. There is little friction between the puck and the ice and so the puck slides easily when it is hit by the player's stick

If you roll something across a surface, friction will cause it to slow down. It will stop at some point. Friction also help things to change direction.

The friction between the ball and the bat helps the ball to change direction

You will need: a small trolley - a forcemeter - different types of surface

You can use a forcemeter to find out about friction. If there is more friction, you will need a bigger force to make something move. Plan an investigation.
You will pull a trolley across different surfaces with a forcemeter.
Predict which surface will produce the most friction. Try using a very smooth surface and a rough surface.
How will you measure this? How will you record your results?
When you have done the test, decide what your conclusion is. If you have time, test other surfaces.

1) When does friction act?
2) Faye loves her garden slide. She finds that when she wears cotton clothes she goes faster than when she wears woollen clothes. Explain why.

What you have learnt

- Friction acts when two surfaces rub together.
- The size of the friction force depends on the two surfaces which are rubbing together.

Talk about it!

Why are some shoes safer to wear on ice than others?