Friction is a force that slows down moving objects or prevents stationary objects from moving . Friction is a contact force . Friction produces heat . For example – A matchstick Friction opposes the motion of an object When one surface moves over another , these grooves and ridges get caught up with each other and slow down the motion . This causes friction .

2. What is friction ?
• Friction is a force that slows down
moving objects or prevents
stationary objects from moving .
• Friction opposes the motion of an
object

3. •Friction is a contact force .
•Friction produces heat .
•For example – A matchstick

5. Causes of friction
• When one surface moves over
another , these grooves and
ridges get caught up with each
other and slow down the motion .
This causes friction .

7. Types of friction
• There are four types of friction :-
1. Static friction
2. Sliding friction
3. Rolling friction
4. Fluid friction
Three
main
types of
friction

8. Static friction
•Static friction is a force that
keeps an object at rest. It
must be overcome to start
moving the object.

10. Sliding friction
•Sliding friction refers to the
resistance created by any two
objects when sliding against
each other.

12. Rolling friction
•Rolling friction , is the force
resisting the motion when a
body (such as a ball, tyre, or
wheel) rolls on a surface.

14. Fluid friction
• Friction on moving objects
through fluids such as air and
water is called Fluid friction .
• This frictional force that fluids
exert on objects is called drag .

15. • It depends on the following reasons
:-
1.Shape of the object .
2.Speed of the object with respect
to fluid .

16. Advantages of friction
• It would be easy to walk .
• Without friction we could not
write.
• Brakes in vehicles help to stop
because of friction .

17. Friction helps to
write and walk
Vehicle stops
due to
friction when
brakes
applied

18. Disadvantages of friction
• It causes wastage of energy
because any object that moves
has to overcome the force of
friction .
• The soles of our shoes wear out
in a few months due to friction .

19. • Friction generates heat .
Sometimes this can be harmful .
The heat produced in a fast
moving machine is very high .
Proper arrangements should be
made to cool the machine ,
otherwise it can get damage .

20. The soles of shoes
being damaged due to
friction

21. Decreasing friction
• Polishing – It smoothens the
surface and thus reduces
friction .
• Lubrication – It can be done with
graphite , oil or grease.

22. • For example - Graphite is used in
machines as lubricant to reduce
friction .
• Streamlining – Streamlined shape
which is rounded in front and
narrow at the back .
• For example – Birds , aeroplanes
(aerodynamic)

23. • Ball bearing – Rolling friction is
less than sliding friction so ball
bearings are used to reduce
friction

24. Streamline
d shape of
a car and a
aeroplane .

25. Ball
bearing
sLubrication
polishing

26. Increasing friction
• Tyres have design and grooves to
increase friction so that they
don’t slide on the wet road .
• To walk easily on ground in rainy
season sand and gravel is placed .

27. • To get a firm grip on the ground
spikes are provided on the shoes
sole used by players .
• Gymnasts apply a coarse
substance on their hands to
improve their grip

28. Spikes in
shoes
Sand and
gravel
Grooves in
tyres
coarse substance
applied by
gymnasts

29. THANK YOU