Pushing the
block means we
are applying the
force to move
the block
Friction is
acting
opposite to
the motion
of the block
Today’s topics
Factors affecting Friction
• Surface
• Weight
• shape
• Lubricants
Types of friction
Water Resistance
Air resistance
Factors Affecting Friction
SURFACE
Rough surface means greater friction
Smooth surface means less friction
Rough surface
Smooth surface
Block is of the
same weight
on rough and
smooth
surface
Weight (in this case surface will
remain the same)
Surface is
same in
both the
cases for
heavy and
light weight
Lubricants
• Why we use lubricants?
• lubricant is a substance
which is more often use to
reduce friction
• Oil
• Wax
• Grease
• Honey
• Even water in some cases
Types of friction
Air Resistance
Water resistance
Air resistance
Air resistance is a frictional force that air pushes against a
moving object.
Air resistance always tries to slows a moving object down.
Example for air resistance
Air resistance on falling objects
How to reduce Air resistance
(shapes of objects)
Air resistance and surface area
Greater
surface area
Smaller surface
area
Air resistance can be increased by
increasing the surface area
Water resistance
• Water resistance is the friction between an objects and the
surrounding water as the object moves through the water
How can we reduce water resistance?
How can fish move easily in water?
To discuss the factor of shape that how it affects friction we know that
streamlined shapes reduce friction, because
streamlined objects has less surface area
It means that greater the surface area greater will be air resistance or
water resistance (friction) , less surface area less (friction)