FrictionFrictionFriction is the force which opposes motion. It always acts in the opposite direction to which the driving force operates.

Friction is the force which opposes motion. It always acts in the opposite direction to which the driving force operates.

Drive forceFriction Force

By Mrs Gibb (2009)

Frictional ForcesFrictional Forces

In this case the applied force is equal and opposite to the friction force, the result is the box will not move, it will be stationary.

Friction is both useful and a problemFriction is both useful and a problem

Friction will slow the skier down, it is opposite the motion force.

Skiers use narrow, smooth ski’s to keep the friction force as small as possible.

When friction is low for example between a snowboard and snow sliding is easy.

When friction is high, for example between a rope and a hand, sliding is difficult

Rough surfaces have more friction than smooth ones

When friction is low for example between a snowboard and snow sliding is easy.

When friction is high, for example between a rope and a hand, sliding is difficult

Rough surfaces have more friction than smooth ones

Friction is both useful and a problemFriction is both useful and a problem

A lack of friction can be a problem…

Imagine if the All Blacks had to play the world cup final in their socks instead of their boots with spriggs!

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Friction is due to the very small irregularities on the surface. It always acts along the surface and opposite to the motion of the object.

Increase:1. Make the surface rougher.

Chains on a car in the snow.

2. Increase the force on the objects.

Removing stuck-on food from a pan.

Increase:1. Make the surface rougher.

Chains on a car in the snow.

2. Increase the force on the objects.

Removing stuck-on food from a pan.

Why we Change the Amount of FrictionWhy we Change the Amount of Friction

Decrease:

1. Use a lubricant.

Put oil in your car engine

2. Switch from sliding to rolling friction.

When moving a refrigerator, put it on a dolly.

3. Smooth the surfaces.

Shaving your legs when you are a competitive cyclist

Decrease:

1. Use a lubricant.

Put oil in your car engine

2. Switch from sliding to rolling friction.

When moving a refrigerator, put it on a dolly.

3. Smooth the surfaces.

Shaving your legs when you are a competitive cyclist

FrictionFriction

1) What is friction?

2) Give 3 examples where it is annoying:

3) Give 3 examples where it is useful:

4) What effect does friction have on the surfaces?