FRICTION
LO: To identify and describe the force of friction
Success criteria:
All should be able to understand and describe frictional force
Most will be able to explain the effects of friction
Some will be able to explain the effects and describe useful and
harmful friction
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2004
What is friction?
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?
It is called friction.
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.
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More about friction
Friction always tries to slow moving objects down.
We say it opposes motion.
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.
There is a maximum value for the frictional force
which depends on:
 the force pushing the two surfaces together;
 the state of the surfaces in contact.
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What are the sources of friction?
Label all sources of friction that can act on this bike.
brake pad
and rim
wheel
bearing
pedal bearing
wheel bearing
air
resistance
or “drag”
One
more? Probably
the most important…
tyre and road
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links in chain
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2004
Effects of frictional forces
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GROUP WORK- RESEARCH
USEFUL AND HARMFUL EFFECTS OF FRICTION
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© Boardworks Ltd 2005
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