cheeck this class 8 science ppt in class 8 students or below can refer this ppt and make their mind map forscience. thank you

1. FRICTION
MADE BY SHIVEN
ROJASARA

2. • In 1826, John Walker, a chemist in Stockton on Tees, discovered
through lucky accident that a stick coated with chemicals burst
into flame when scraped across his hearth at home. He went on
to invent the first friction match. Until the first half of the
nineteenth century, the process by which fire was created was
slow and laborious. Walker's friction match revolutionized the
production, application and the portability of fire. Walker sold
his first "Friction Light" on the 12th April 1827 from his
pharmacy in Stockton on tin 1826.

3. Static friction is a force that keeps an object at rest. If a
small amount of force is applied to an object, the static
friction has an equal magnitude in the opposite
direction.
standing friction:- static
moving friction:- kinetic

4. • Kinetic friction is a force that acts between
moving surfaces. An object that is being
moved over a surface will experience a force
in the opposite direction as its movement.
The magnitude of the force depends on the
coefficient of kinetic friction between the two
kinds of material.

5. Friction is said to be a necessary evil because it is
useful as well as harmful. friction helps us to walk,
write, hold things, lift objects.
Without friction many essential processes can not be
done.

6. a. That's why rubbing your hands together makes them
warmer. ... Friction causes the molecules on rubbing
surfaces to move faster, so they have more energy.
This gives them a higher temperature, and they feel
warmer.
match
stick
Match box

7. 1) Force of friction :-
Force of friction is the force which opposes the motion of an object
over a surface.
The force of friction acts between the object and the surface.
Eg :- A ball rolling on ground gradually slows down and comes to
rest due to force of friction between the ball and the ground.
If we stop pedaling a bicycle, it gradually slows down and
comes to a stop due to force of friction between the wheel and
the road.

8. Factors affecting friction :-
Friction depends upon two factors. They are :-
i) Nature of the surfaces in contact. ( The smoothness
of the
surfaces).
ii) How hard the surfaces press together.
Friction is less on a smooth surface.
Friction is more on a rough surface.

9. • Cause of friction :-
• Friction is caused due to the interlocking of
irregularities between the
• two surfaces in contact.
• Smooth surfaces have minute irregularities
between the two surfaces.
• Rough surfaces have larger irregularities
between the two surfaces.
• So force of friction is more if the surfaces
are rough.

10. • Rolling friction (or rolling resistance) is the resistive
force that slows down the motion of a rolling ball or
wheel. When a force or torque is applied to a
stationary wheel, static rolling friction holds back the
motion

11. • The term sliding friction refers to the resistance
created by two objects sliding against each other.
This can also be called kinetic friction. Sliding
friction is intended to stop an object from moving.

12. THANKYOU