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Lesson 6 of 10

Friction

I can describe the characteristics of friction forces, explain what causes friction and describe how friction can be reduced.

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View unit
Lesson 6 of 10
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Friction

I can describe the characteristics of friction forces, explain what causes friction and describe how friction can be reduced.

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Lesson details

Key learning points

  1. Friction is the force of one surface gripping or rubbing on another.
  2. Friction prevents or slows down movement between surfaces.
  3. Friction is caused by the roughness of surfaces.
  4. Lubricants are substances added between two surfaces to reduce friction.

Keywords

  • Friction - Friction is the force of one surface rubbing or gripping on another.

  • Rough - Rough surfaces are uneven or irregular, they are not smooth.

  • Irregularities - An irregularity is something different to what is expected.

  • Microscopic - If something is microscopic, it is so small you need a microscope to be able to see it.

  • Lubricant - A lubricant is a substance added between two surfaces to reduce friction.

Common misconception

Friction is not a force.

Provide examples of friction slowing objects and preventing them from moving when they are pushed.

Explore the word 'irregularity' when it comes up in this lesson. Students will be familiar with the word 'regular' to describe food (e.g. 'regular fries') or transport services, as well as regular/irregular shapes from KS2 maths.
Teacher tip

Licence

This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

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6 Questions

Q1.
Which is the best description of a friction force?

The downwards force due to gravity.
Correct answer: The force of one surface gripping or rubbing on another surface.
The force from the air that slows down moving objects.

Q2.
Which picture shows a friction force?

An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz

Q3.
Which factor can affect the size of the friction force acting when an object slides over a surface?

The colour of the surface.
Correct answer: How rough the surface is.
How transparent the surface is.

Q4.
Give the correct direction: Friction forces always act on a moving object.

Correct Answer: backwards, backward, back

Q5.
Which sentences describe the correct effects that friction forces can have on objects?

Correct answer: Friction forces slow down moving objects.
Friction forces can repel objects away .
Correct answer: Friction forces can heat up objects.
Friction forces pull objects back down towards planet Earth.

Q6.
An object is sliding along a surface. Which of the following can reduce the friction force?

Correct answer: If the surface was smoother.
If the surface was rougher.
Correct answer: If the surface was sanded down.
Correct answer: If a slippery liquid or grease was added between the object and the surface.

Assessment exit quiz

Download quiz pdf

6 Questions

Q1.
Which best describes what a friction force is?

The force of one surface touching another surface.
The force of one surface repelling another surface.
Correct answer: The force of one surface gripping or rubbing on another surface.

Q2.
Which picture shows the friction force of the ice on the sliding puck?

An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz

Q3.
The size of a friction force between dry surfaces is affected by how the surfaces are.

Correct Answer: rough, smooth, bumpy, irregular

Q4.
Any substance added between two surfaces to reduce friction is called a ...

Correct Answer: lubricant

Q5.
Which gives the best explanation of how lubricants reduce friction?

Lubricants are slippery.
Lubricants should stay in place and not promote rusting.
Correct answer: Lubricants keep surfaces slightly further apart.
Lubricants are liquids so can flow.

Q6.
Identify the false statement.

Friction forces can slow down an object.
Friction forces can prevent movement.
The size of the friction force between two surfaces can change.
Correct answer: Friction forces only act when there is movement.
Friction occurs when tiny irregularities catch, producing backwards forces.

Lesson appears in

UnitScience / Forces

Science

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