for the grade 8 students very useful.it tells about friction in an easier way.

1. AREYOUREADY?45109876

2. FRICTION

3. The force which always
opposes the motion of
one object over another
object in contact with it,
is called friction.

4. The force of friction always opposes
the motion of one object over
another object.
So, the force of friction acts in a
direction opposite to the direction
in which an object moves.

5. CAUSE OF FRICTION :
The interlocking of irregularities of the two
surfaces opposes the motion of one object
over the other and gives rise to force of
friction.
Thus, friction is caused by the interlocking of
irregularities in the surfaces of the two
objects which are in contact with each other.

6. The force of friction is greater if
very rough surfaces are
involved.
The spring balance is a device
which is used for measuring
force acting on the object.

7. FACTORS AFFECTING
FRICTION :
• The nature of the two surfaces
(smoothness or roughness of the
two surfaces).
• The force with which two surfaces
are pressed together.

8. Static friction
Sliding friction
Rolling friction.

9. STATIC FRICTION :
The maximum frictional force
present between any two objects
when one object just tends to
move or slip over the surface of
the other object, is called static
force.

10.  The frictional force present when one
object moves slowly (or sides) over
the surface of another object, is known
as sliding friction.
 The sliding friction is smaller than the
static friction.

11. ROLLING FRICTION :
When an object (like a wheel) rolls
over the surface of another object,
the resistance to its motion is
called rolling friction.
Rolling friction is much less than
sliding friction.

12. ADVANTAGES
OF FRICTION

13. Friction enables us to
walk without slipping.

15. Friction enables us to
write and draw on the
paper.

17. DISADVANTAGES
OF FRICTION

25. METHODS OF
INCREASING
FRICTION

26. Grooves are made in soles
of shoes to increase friction
and prevent slipping.

31. METHODS OF
REDUCING
FRICTION

34. Friction can be reduced by using ball
bearings between the moving parts of
machines.

35. FLUID
FRICTION

36. • Those substances which are able to
flow easily are called fluids.
• Water and Air are the most common
fluids.
• There is friction whenever an object
moves through a fluid.
• The frictional friction exerted by a
fluid is called drag.

37. • The magnitude of frictional force (or drag)
exerted by a fluid on an object moving
through it depends on four factors :
1. Speed of the object
2. Shape of the object
3. Size of the object
4. Nature of the object

38. • The objects having streamlined shapes face much
less frictional force when moving through a fluid
than the objects which do not have streamlined
shape.
• Larger the size of an object moving through a
fluid, greater will be the frictional force acting on
it.
• Higher the vicosity of fluid, greater will be the
frictional force acting on the object moving
through it.

39. • The fluid friction can be reduced by giving
special shape called streamlined shape to the
objects which move through fluids.
• For example, Dolphins are streamlined by nature
to reduce the friction with water.

40. QUEEN BEES OF
LAST BENCHES
V.ASMITHA
S.J.AKSHAYANA
E.GIRIDHARA LAKSHMI
B.JANANI
K.PRIYA