Friction

Aims:

TBAT describe friction

To know how friction can be reduced

To investigate factors that affect friction

TBAT explain how friction can be useful

If you rub your hands together they get warm. There is resistance to the rubbing motion.

What is the name of this resistive force called?

What causes this force?

Your hands might look smooth, but on a microscopic level they have rough surfaces. So when you rub your hands together you feel the resistive force of friction.

What is friction?

It is called friction.

Friction always tries to slow moving objects down. We say it opposes motion.

There is a maximum value for the frictional force which depends on:

More about friction

Friction is created whenever two touching objects or surfaces move past each other.

Friction also occurs when things move through air. This is called air resistance or drag.

the force pushing the two surfaces together; the state of the surfaces in contact.

One more? Probably the most important…

tyre and road

brake pad and rim

wheel bearingwheel

bearing

pedal bearing

links in chain

air resistance or “drag”

What are the sources of friction?

Friction

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?