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7.2 The two sides of friction
How did the ancient Useful friction
Egyptians manage The gecko in the previous lesson
to move huge blocks uses friction as a way of keeping
of stone over long itself attached to walls and
textbooks nis edu kz
distances to build the ceilings. The same is true of most
other insects and animals around
pyramids?
the world that are able to climb
steep and tall surfaces. Humans
make good use of friction as well –
in fact, friction is everywhere!
Friction in engineering is an
incredible force that we could not
live without. Think of old bridges
or different types of vehicle – they
all rely on friction. But of course,
friction can be dangerous too.
This picture shows one idea about
how the stones were moved, but Let us consider an example of transporting loads from one place
there are many others
to another. Some people drag loads across the ground and others
transport loads using wheels (often a trolley).
When dragging a load across the floor, a sliding
friction force occurs; and when transporting a
load on wheels, a rolling friction force occurs.
OVER TO YOU!
How do you think these different types of friction compare? Can
you think of other examples where you use wheels to roll objects
instead of dragging them?
Unwanted heat – non-useful friction
Sometimes friction is not so helpful for the task we have to perform.
When using machines with lots of moving parts, for example, friction
becomes a problem.
As these parts are in contact with each other, they have friction between
them. Their constant movement means that this frictional force will
eventually tear the contact between the surfaces and also cause the
A car’s combustion engine pistons temperature to increase.
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