Friction is the force opposing motion between two surfaces in contact and varies based on weight and surface irregularities. It can be classified into static, kinetic, sliding, and rolling friction, with rolling friction being less than sliding friction. While friction has advantages such as aiding movement and stopping, it also has drawbacks like energy wastage and increased wear.

4. MAGNITUDE OF FORCE

13. Friction is the
force that
opposes the
motion when
two surfaces
are in contact,
move or tend
to move with
respect to
each other

17. of an object
n
se
se
t
WEIGHT OF AN OBJECT
• Friction increases with increase in weight

18. CAUSE OF FRICTION
• Friction depends on the surface of
contact of bodies
• Microscopic examination of
surfaces reveal that all the
surfaces have irregularities
• When two surfaces slide over each
other the irregularities of these
surfaces interlock with each other

20. Static friction
• Frictional force that acts
on a static object or object at
rest is called static friction.
• The maximum force required
to move the object from rest
is called limiting friction

21. KINETIC FRICTION
• The force of friction that slows down an
already moving object and eventually brings
to a stop

23. Sliding friction
• The frictional force
that acts on sliding
objects
• When an object
slides the
irregularities do
not get enough
time to interlock

24. Rolling friction
• The frictional force that
acts on rolling
objects
• Is rolling friction
smaller than sliding
friction?
Yes rolling friction is less
than the sliding friction

26. The resistance offered by fluids on the objects moving
through them
Fluid friction is otherwise called as DRAG
• It depends on:
The shape of the object
Speed of the object
The nature of the fluid
MOTION OF OBJECTS IN FLUIDS

27. Drag due to water and air
• The body that moves
through fluids are made
streamlined so that they
experience minimum
amount of friction
• Body of Ships, Planes, Birds
are all streamlined so that
the fluids offers least possible
friction

28. Advantages of friction
• Help us to walk
• The vehicles to move
• Help us to stop ourselves or
any moving object
• To write
• To light a match stick
• To hammer a nail

29. Disadvantagesoffriction
• Wastageofenergy
• Increaseinfuel
consumption
• Wearandtear
• Productionofunwantedheat
• Productionofunnecessarynoise

31. Increasing friction
• Deep groves( treads) on tyres of
vehicles
• Applying sand or powder to increase grip
before lifting heavy objects
• Grinding stone used in kitchen
• Handles of cricket bats
• Screw for nails
• Designs on tiles used in bathrooms