Slide 1 : FRICTION A ball rolling through the ground comes to rest after sometime A moving swing stops after some time When the switch of a fan is put off, it stops after rotating for some more time.
Slide 2 : Friction is the force acting between two surfaces in relative motion
Slide 3 : Friction always acts in a direction opposite to that of motion
Slide 4 : What is the direction of friction? A falling rain drop A train traveling towards north A boat moving towards west on still water A car traveling towards east An artificial satellite moving in space
Slide 5 : WHAT CAUSES FRICTIONAL FORCE ? Surfaces in contact as viewed through a microscope
USES OF FRICTION : USES OF FRICTION We can walk because of friction
Drive vehicles safely through roads
Hold things
Parachutes land safely due to friction of air
Meteors burn away before reaching the surface of earth
ABSENCE OF FRICTION MAY BE DANGEROUS : ABSENCE OF FRICTION MAY BE DANGEROUS If you step on a banana peel, you may skid
Cyclists skid on oily roads
People skid and fall on mossy surfaces
It is difficult to climb coconut trees during rainy season
METHDS TO DECREASE FRICTION : METHDS TO DECREASE FRICTION POLISHING SURFACES
STREAM LINING
ROLLER BEARINGS AND BALL BEARINGS
LUBRICANTS
SOMETIMES WE TRY TO DECREASE FRICTION AND SOMETIMES WE TRY TO INCREASE IT. : SOMETIMES WE TRY TO DECREASE FRICTION AND SOMETIMES WE TRY TO INCREASE IT. Apply lubricants in machine parts
Boric powder is sprinkled on carom boards
Thieves apply oil all over their body
Tapering end of racing cars Use rubber bushes at the bottom of legs of furniture
Grooves at the bottom of slippers
Rubberized roads
Badminton players use band around the palm