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# CBSE Class 8 Physics Notes for Chapter 2 Friction

CHAPTER 2 FRICTION

FRICTION
Friction is a contact force which acts on a moving object in the direction opposite to the direction of the motion of the object.

FACTORS AFFECTING FRICTION

• Nature of the surfaces in contact
• How hard the surfaces are pressed together

Friction is less on a smooth surface.
Surfaces pressed hard against each other have more friction between each other.

FRICTION: A NECESSARY EVIL
Without friction, we won’t be able to walk. Without friction, we won’t be able to write. Friction plays an important role in our daily life. It is a necessary evil.

INCREASING AND REDUCING FRICTION
To increase friction, the surface is roughened or grooved. For e.g. Soles of the shoes are grooved.
To reduce friction, the surface is smoothened or lubricated. For e.g. Grease is used to reduce the friction between the moving parts of vehicles.

REDUCING FRICTION USING WHEELS
Rolling friction is less than sliding friction. Therefore, wheels are used in luggage bags so they can be moved easily.

FLUID FRICTION
Gases and liquids are commonly known as fluids. The frictional force exerted by fluids is called fluid friction or drag,
Fluid friction can be reduced by streamlining the body. Streamlining is changing the shape of an object in such a way that the drag is minimum.