FRICTON

PRESENTED BY

SANDHYA V S PHYSICALSCIENCE

FRICTION

Suppose you decide to ride a skate board

You push off the ground and start moving

According to Newton’s second law

of motion ,if no

other forces are acting

on your skateboard , you

will continue to move….BUT

The reason is that there exist a force

between the

ground and lower portion of the

skateboard, called

FRICTIONAL FORCE.

WHAT IS FRICTION

Friction is the force which opposes relative

motion

between two surfaces in contact with each other

What causes FrictionEven though a surface may look smooth, if you magnify thesurface it isn’t smooth.

Everything is made of molecules. The molecules cometogether to make bumps. Some surfaces have moleculesthat leaves large bumps and some leaves small bumps.

Micro welds occur when two bumpy surfaces are rubbed upagainst each other they stick together.

Types of frictions

Static frictionFrictional force between two surfaces before there

is a relative force between the surfaces in contact.

Kinetic friction It is the force of friction which calls in to play when

there is relative force between the surfaces.

Rolling friction Rolling friction between two surfaces in contact is the force of

friction which calls into play when a body rolls over another.

Sliding frictionsliding friction is the force that opposes the motion of two

surfaces sliding past each other.

ADVANTAGES OF FRICTION

Helps us in walking conveniently. It save us from

slipping.

Helps us in writing on piece of paper.

Helpful in eating and drinking

Lighting a match stick by rubbing.

Nails and screws join two surfaces due to the

friction.

we can not climb a tree.

Trains can run on the rails.

In fact life become impossible if there is no

friction in nature.

DISADVANTAGES OF FRICTION

Due to friction the whole energy given to a machine is not converted in to useful work; a portion of energy is wasted to overcome friction.This reduces the efficiency of the machine. The energy used in overcoming friction appears as heat. Moreover, friction causes wear and tear of the moving parts of the machine due to rubbing.

Thus

FRICTION IS A NECESSARY EVIL

TO INCREASE FRICTION

It is not possible to walk or drive through

muddy and slippery roads. For this sand and

gravels are spread to reduce friction

Tyres of our vehicles also the soles of the shoes are

grooved.

Mountaineers also wear spiked shoe.

To overcome skidding along a slippery surface we adopt

measures to increase friction.

TO REDUCE FRICTIONReduce the area of contact of two surfaces.

Making the surfaces as smooth.

Lubrication can reduce friction.

Using ball bearings.

THANK YOU