I have expertise in making educational and other PPTs. Email me for more PPTs at a very reasonable price that perfectly fits in your budget. Email: parmarshivam105@gmail.com Chapter - 12, Friction, Science, Class 8 FORCE OF FRICTION RELATIVE MOTION FACTORS THAT CAN AFFECT FRICTION TYPES OF FRICTION STATIC FRICTION SLIDING FRICTION ROLLING FRICTION FLUID FRICTION ADVANTAGES OF FRICTIONAL FORCE DISADVANTAGES OF FRICTIONAL FORCE HOW CAN WE REDUCE OR INCREASE FRICTION? INCREASING FRICTION REDUCING FRICTION HOW WHEELS REDUCE FRICTION? FLUID FRICTION FLUID FRICTION COMPRISES INTERNAL AND EXTERNAL -FRICTION Every topic of this chapter is well written concisely and visuals will help you in understanding and imagining the practicality of all the topics. By Shivam Parmar (Entrepreneur)

1. Chapter - 12
Friction
By Shivam Parmar
(Entrepreneur)
Email for more PPTs at a very reasonable price.
Email: parmarshivam105@gmail.com

2. FORCE OF FRICTION
• Friction is a force that comes
into play when two surfaces
come in contact with each
other.
• The Frictional force or the force
of Friction acts in the opposite
direction of the motion of the
object.
• The force of Friction opposes
the relative motion between
the surfaces of two moving
objects.

3. RELATIVE MOTION
When one object moves relative to another it is called a relative motion.

4. FACTORSTHAT
CAN AFFECT
FRICTION
• The irregularities of a surface: If we move an object with
has an irregular or rough surface on another surface which
is also irregular, the force of Friction will be high in this case
and the movement of the object would be restricted.

5. The regularity of a surface or its smoothness: If the surfaces of either the
objects or are smooth, the force of Friction would be less and the object
would move easily over the surface. Even smooth surfaces have a certain
irregularity.

6. If two surfaces are pressed hard: the force of Friction increases between
two surfaces if they are pressed hard and hence the movement of the
object becomes restricted. However, if there is no pressure the object
can easily move.

7. TYPES OF FRICTION
1. Static Friction:
The Frictional force that
comes into play until an
object starts moving is called
static Friction. An object has
to overcome the static
Friction force in order to start
its movement.

8. 2. Sliding Friction:
Sliding Friction comes into
play whenever an
object moves along the
surface of another object.
Such a movement is
called ‘slide’. Hence, sliding
Friction is the force that
opposes the movement or
slide of an object.

9. 3. Rolling Friction:
When an object is rolling on a surface the force of Friction which acts
upon it is called rolling Friction.

10. 4. Fluid Friction:
When an object moves in
a fluid, the fluid exerts
a fluid Friction upon the
object. It is also called air
Friction (when
the medium of travel is
air) and viscous Friction
(when the medium
of travel is water).
Rolling Friction < Sliding Friction < Static Friction

11. ADVANTAGES OF
FRICTIONAL
FORCE
Frictional force is necessary for various
purposes in our daily lives such as:
It allows us to walk on the earth surface.
It allows us to write with a pen on a surface or
a paper.
It allows us to fix a nail in the wall.
A moving object would never be able to come
to the state of rest without the Frictional force.

12. It would not be
possible to drive any
automobiles on the
road without the
Friction force.
It would not be
possible to construct
any buildings without
the Frictional force.

13. DISADVANTAGES OF
FRICTIONAL FORCE
• Frictional force results in wear and tear
of objects such as the moving parts of a
machine, the tyres of a vehicle, sole of
the shoes etc.
• It also results in the production of heat.
In the case of machines, the production
of heat leads to wastage of energy.
• The Frictional force also leads to a
decrease in the speed of a
moving object or some time stops it.

14. It can lead to noise
pollution in certain cases.
For instance, aircrafts
produce loud sound due to
the resistance of the air.
And sometimes friction
causes fire in forests too.

15. HOW CAN WE
REDUCE OR
INCREASE
FRICTION?
Increasing Friction:
Sometimes we need to increase
Friction so as to avoid slipping of
objects, for example:
The sole of the shoes is grooved
so that the Friction between our
feet and ground increases and
we can walk safely.

16. The tyres are treaded so
that they can have a
better grip over the ground
and allow the smooth
movement of the vehicles.
Brake pads are used in
bikes to stop them
suddenly from moving by
increasing the amount
of Friction.

17. Reducing Friction:
Sometimes in order to have a smooth
movement of an object we need to reduce
Friction. For example,
The powder is sprinkled over the carrom board
to decrease the Friction between the board’s
surface and the striker.

18. • Grease is used in bicycles
and other motors
or different parts of a
machine to reduce Friction
and increase their efficiency.
• Oil is applied on the hinges
of the door so that they can
move easily.

19. • Applying substances like oil,
grease or powder allows in
smooth movement as they
block the irregularities of a
surface. The substances that
can reduce the amount of
Friction between different
objects are called lubricants.
However, we can never
reduce Friction to a level of
zero. There are always some
irregularities present on the
surface.

20. HOW WHEELS
REDUCE
FRICTION?
• We know that when an object rolls over a
surface rolling Friction is produced which
resists its motion on the surface.
However, its magnitude is lesser than the
static and sliding Friction.
• Wheels are circulating objects that turn
around a center point.
• The wheels allow an object to roll over a
surface rather than allowing them to slide
over the surface.
• This results in less Friction and hence easy
movement of the object.

21. • Rolling Friction is also used in the
parts of machines that are moving
continuously.
• In this way, the sliding Friction is
removed with the help of rolling
Friction and therefore the adverse
effects of Friction such as the
production of heat or wear and tear
of the mechanical parts are also
reduced.
• For instance, ball bearings are being
used in fans and bicycles to reduce
Friction.

22. FLUID FRICTION
Gases and liquids are
generally known as
fluid. Similar to solid,
fluids also provide
friction. The friction of
fluid increases with
the speed of object
moving through it and
speed of fluid.

23. Objects which are made to move in
fluid are made streamlined shape to
reduce friction offered by fluid. The
shape of aeroplane, ship, boat, birds
and fish are made streamlined shape.
A shape which is pointed on both
ends and wide at the middle is called
streamlined shape which facilitates
easier movement through fluids.

24. FLUID FRICTION COMPRISES
INTERNAL AND EXTERNAL FRICTION
Fluids comprise of internal
Friction that occurs between
the molecules of a liquid as
they are also in motion. The
viscosityof a liquid, therefore,
depends upon the internal
Friction.
An external Friction in fluids is
the force exerted by the fluid
on the object that flows
through it.

25. • As an object travels in a fluid it loses its energy in
order to overcome the fluid Friction. Hence, things
that can easily flow in fluids have special shapes.
• For instance, ships and boats have a particular shape
that allows them to resist fluid Friction.

26. Birds and aeroplanes have a
specific shape that
allows them to fly in the air.
Fishes also have a specific
shape such as a tail and fins
that allow them to swim
continuously in water
and even prevent the loss of
energy due to fluid Friction.

27. Thank You
I have expertise in making educational
and other PPTs. Email me for more PPTs
at a very reasonable price that perfectly
fits in your budget.
Email: parmarshivam105@gmail.com