Lesson 5 of 7

Friction

Goal: Describe friction and when it helps or hinders.

Puzzles for this lesson

Friction is a force between two surfaces that touch. It acts against sliding.

Rough surfaces grip more. Even a smooth surface has tiny bumps that catch on the other surface.
Friction is useful in brakes, in tyres on a road and under your shoes.
Friction is a nuisance in machines. It wears the moving parts and makes them hot. Oil is a lubricant: it reduces friction.

Your turn

This lesson’s activity starts here in a moment.

I can say what causes friction.I can give one useful and one unhelpful example.

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Force A push or a pull

Friction Opposes sliding between two surfaces

Lubricant A substance, such as oil, that reduces friction

For teachers: AQA 3.1.3 · Pearson Edexcel 39.6