Friction

Why is friction vital in helping us to move?

Starter:How do these objects use the idea of friction to do their job?

End of Term Exam

B5 exam – Wed 12th Feb

That weekMonday – finish physicsTuesday – revise B5Wed – ExamThurs – go over exam

Week back – p4 exam (sorry)

What do McFly know?

Harry: Friction is a type of force which

usually prevents sliding.

Tom: Friction is caused by pressure between 2 things.

Dougie: Friction is an energy that slows things

down.

Learning outcomes

revise that friction is a force that acts in a direction to prevent (or tend to prevent) sliding motion

explain how an interaction pair of forces enables a wheel to make a vehicle move

explain how friction is caused by the irregularities of surfaces

explain how the friction force balances the applied force up to a limit (for any given situation)

Why is friction vital in helping us to move?

Starting to Walk

• How does friction help us walk?

revise that friction is a force that acts in a direction to prevent (or tend to prevent) sliding motion

One foot pushes back on the ground. What do you know about

forces??! .

force exerted by foot on ground

revise that friction is a force that acts in a direction to prevent (or tend to prevent) sliding motion

• The ground pushes back – an interaction pair of forces.• It is the forward force, on your foot, that enables you to move

forward.

force exerted by ground on foot

force exerted by foot on ground

revise that friction is a force that acts in a direction to prevent (or tend to prevent) sliding motion

How do the wheels on our car enable us to move?

Watch these clips and work out how the wheels enable our cars to move forwards.

car driving off/mud/ice• http://www.youtube.com/watch?v=nfV87TgYH78

• http://www.youtube.com/watch?v=iq8Bi78npnI

• http://www.youtube.com/watch?v=Wp2sqrfGSPIexplain how an interaction pair of forces enables a wheel to make a

vehicle move

Other uses of Friction

• Think – Pair – Share :

• What possible uses does friction have?

Why is friction vital in helping us to move?

From Stationary ….. Will the box move?

Why is friction vital in helping us to move?

From Stationary ….. Will the box move?

Why is friction vital in helping us to move?

From Stationary ….. Will the box move?

What causes friction.

Make a list of surfaces that offer lots of friction, and those that only offer some.

What are the key similarities between them?

Think – Pair – Share

• How does friction work?

Task

• Sketch a “zoomed in” view of a surface with good friction and explain how the surface causes the friction.

Task

Complete the friction learning mat.

Why is friction vital in helping us to move?

Jelly & Chopstick Experiment

Soap experiment

Complete Find Someone Who