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FRICTION

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FRICTION Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction resists relative lateral motion of two solid surfaces in contact.

The coefficient of friction (COF), often symbolized by the Greek letter µ, is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together. The coefficient of friction depends on the materials used; for example, ice on steel has a low coefficient of friction, while rubber on pavement has a high coefficient of friction. Coefficients of friction range from near zero to greater than one.

COEFFICIENT OF FRICTION

There are four types of friction: Static , Kinetic , Rolling, and Fluid friction.Static, sliding, and rolling friction occur between solid surfaces. Static friction is strongest, followed by sliding friction, and then rolling friction, which is weakest. Fluid friction occurs in fluids, which are liquids or gases.

TYPES OF FRICTION

Static friction comes into play when a body is forced to move along a surface but movement does not start. The magnitude of static friction remains equal to the applied external force and the direction is always opposite to the direction of motion.

STATIC FRICTION

Rolling frictional force is a force that slows down the motion of a rolling object. Basically it is a combination of various types of frictional forces at point of contact of wheel and ground or surface .

ROLLING FRICTION

Kinetic friction denoted as μk comes into play when a body just starts moving along a surface. When external applied force is sufficient to move a body along a surface then the force which opposes this motion is called as kinetic frictional force.

KINETIC FRICTION

When a body moves in a fluid or in air then there exists a resistive force which slows down the motion of the body, known as fluid frictional force.

FLUID FRICTION

1.friction helps us to walk. When we press the ground with our foot backward, we receive a forward reaction due to friction between our foot and the ground .Had there been no friction the foot will simply slip away. 2.friction help us to write on the backboard or on a paper. 3.Brakes make use of friction to stop vehicles. 4.friction helps to transmit power from the motors and engine to other machines by making use of belts and clutches.

ADVANTAGES OF FRICTION

1.Friction cause unnecessary wear and tear of the machinery. 2.Due to friction between the moving parts of a machine heat is produced , which affects the working as well as the life of a machine. 3.A part of useful energy is dissipated in overcoming the friction.

DISADVANTAGES OF FRICTION

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