User:Vathsala A/sandbox

FORCE OF FRICTION
The force which opposes the relative motion between two surfaces in contact.

Friction always acts opposite to the direction of motion.

CAUSED BY
Irregularities on two surfaces in contact.

FACTORS AFFECTING FORCE OF FRICTIO N
1.Smoothness of surface.

2.Pressing of objects.

ADVANTAGES OF FRICTION

 * 1) To walk
 * 2) To stop/slow down vehicles
 * 3) To write/draw on paper
 * 4) To tie knots
 * 5) To fix nails
 * 6) To cut wood
 * 7) To pick and hold things    etc..,

DISADVANTAGES OF FRICTION

 * 1) Wears away soles of shoes
 * 2) Wears out brake pads of vehicles
 * 3) Wears out steps of stair case
 * 4) Heat produced because of friction damages the machine
 * 5) Friction acting between moving parts of the machine,reduces the efficiency of the machine    etc..,

INCREASING AND DECREASING OF FRICTION
The answer for the above questions are to increase friction.The key reason is that the dry soil or the spikes in the above case increases the irregulaties(cause of friction) which results in increase of friction. In the above case oil and lubricants are used to reduce the friction of cycle chain and stiker on carrom.
 * 1) Why do kabbadi players rub their hands with dry soil?
 * 2) Why athelete shoes have spikes?
 * 1) Have you come across people applying oil to cycle chain?Why do they apply?
 * 2) Why do they sprinkle powder on carrom board?

The substances which prevent friction is called   lubricant . 

Static friction
Friction acting on sliding objects.

Sliding friction
Friction acting on sliding objects.

Rolling friction
Friction acting on rolling objects.

Fluid friction
Friction exerted by fluids(gases and liquids are called fluids).