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7.1 The meaning of friction
A spark ignites when
you use a lighter. The
soles of your shoes,
and car tyres, quickly
textbooks nis edu kz
become worn because
of friction. A gecko
attaches itself to the
ceiling. How do you
think these things
happen?
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When physical bodies/objects are in contact with each other, a force
emerges between the surfaces of these objects. The friction force is the
force exerted by a surface when an object tries to move across it – both
before it moves and during its movement. There are different types of
friction, depending on the type of movement between the surfaces.
The frictional force is typically in the opposite direction to the motion,
but not always. For example, if a brick slides across the surface of a table,
then a friction force occurs between the surface of the table and the
brick in the direction opposite to the motion.
Types of friction
Types of frictional
forces between surfaces
Static friction Sliding Rolling
force friction force friction force
● When a physical body/object is at rest but in contact with a surface,
static friction occurs.
● When a physical body/object is sliding across the surface of another
one, a sliding friction occurs.
● When a physical body/object is rolling on the surface of another one,
a rolling friction occurs.
INV In this activity you should investigate the main types of friction,
looking at the force required to make an object move/slide across a
specific surface. Make a prediction, draw an appropriate table of results
and choose adequate equipment.