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
4.
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 .
6.
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
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 .
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
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