Factors Affecting Friction:Nature of Surface Video Lecture - Class 8

hello friends this video on friction
part 3 is brought to you by exam for
your calm no more fear from exam before
that let us talk about the factors
affecting friction so what are the
different factors which give rise to
friction or on which frictional force is
dependent now primarily there are two
important factors which affect friction
one is smoothness of the surfing so
basically how smooth or how rough the
surface is that decides how much the
friction will be because as I said if
you are considering a perfectly smooth
surface a surface which is extremely
smooth so there is no roughness involved
so that surface will not have any
friction so if at all you are talking
about a perfectly smooth surface so for
a perfectly smooth surface the
frictional force that is force of
friction will be equal to zero however
this is also true that a perfectly
smooth surface doesn't exist in reality
so it is just a hypothetical or a
theoretical statement but in reality
there is no surface which is perfectly
smooth even the most smooth looking
surface also has irregularities on its
surface so there is nothing called
perfectly smooth surface which exists in
reality so the first factor is how
smooth or how rough the surfaces so
based on that the friction will change
so if a surface is smooth the friction
will be less if a surface is rough the
force of friction will be more secondly
how tightly the surfaces are held
together now as I mentioned that
friction comes into picture only when
two surfaces are in contact with each
other now when I say in contact there
are chances that the two surfaces they
are just touching each other there is a
probability where the two surfaces are
like in a good way they are touching
each other like let us take an exam so
let us suppose this is one surface and
this is another surface okay so maybe
this is a table and this is this one is
a table and this is some
object so let us consider the same table
and on the same table you have an object
like this so this is another object now
again on the same table you have let us
say a bigger and a heavier object like
this this is a bigger and heavier object
this is a comparatively smaller object
and this is also a smaller object with a
different shape now in all these three
cases just try to look at the surface of
contacts where are they in touch with
each other so here if you see the two
surfaces are in contact with each other
but they are not held very tightly they
are just touching each other at a point
but since they are in contact so the
friction will come into picture if you
consider this case so here if you see
compared to first scenario in second
scenario the surfaces are more tightly
held to each other because they are more
in contact with each other now you
consider the third scenario so here you
see since the ball boxes heavier and
bigger so it is like even the box
becomes heavier or let us see if you are
pushing this box from above so you are
applying some force from above so that
means basically you are trying to press
this box hard against this surface so
these two surfaces are very tightly held
together right now the more tightly the
surfaces are held together the more
would be the force of friction so in
these three scenarios one two and three
the force of friction would be maximum
in three then the force of friction
would be minimum in one so it is not
only the roughness and smoothness of the
surface which decides how much the
frictional force would be it is also a
factor that how tightly the surfaces are
held together so that also is a very
important factor to decide how much
friction it would discourage the first
factor in little more detail that how
the smoothness or roughness of a factor
surface affect friction now you will see
that friction is lesser on a smooth
surface than a rough one so it is always
less on a smooth surface so
if you don't believe me let us look at
some examples just try to stretch your
legs when you are doing your exercise or
yoga session or maybe your aerobics
class and you will find that on a rough
floor it is little difficult for you to
stretch but if the floor is smooth
enough maybe you can smoothen the floor
by applying some by applying some of oil
or water or powder or the floor and then
the flow turns sleeping and then you try
to do the same stretching and you will
feel that it becomes easier to stretch
now that's because your legs tend to
slip over the floor because the floor
has turned slippery therefore the floor
offers less friction so the opposition
is less to your motion and therefore you
are able to move your legs more easily
so stretching your legs becomes easy on
a smoother surface when compared to a
rough surface so that is one example
which tells you that smoother surface
offers less friction let us look at
another example just try driving your
car on a smooth road versus a rough road
so a smooth road with lesser bumps and a
rough roll with a lot of bumps lot of
and even stones and rocks here and there
so these two types of roads what do you
see that more force is needed to be
applied to make the car move on a rough
surface because here you have a lot of
bombs ups and downs so you need to apply
more force to drive your car because
your car filings it's difficult to move
on a rough road that's because the
friction is more here so when the
friction is more so that means the
opposition to motion is more because
friction always opposes motion so the
movement of the car becomes difficult
but still if you want to make your car
move on the rough surface you need to
apply more force now on the contrary
when you consider the smooth surface so
here you see that your car moves
absolutely perfect and it moves at a
higher speed as well so you just drop me
to applying a lot of force to make your
car move
that's because here the friction is
less therefore the applied foods which
is required is also less because
opposition is less so the movement just
happens on its own so you do not really
need to apply some extra force to make
your car move so these examples show
that if the surface is smooth friction
is less if the surface is rough friction
is more thank you please visit
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