Frictional Forces

Prepared By: Essha Maryam and Iman


A force is a push or pull acting upon an object as a result of its interaction with another object. There are a variety of types of forces.

Different types of forces:

Contract forces

Frictional Forces

Tension Forces

Normal Forces

Air resistance Force

Applied Force

Spring Force

Frictional Force:

The frictional force is the force exerted by a surface as an object moves across it or makes an effort to move across it.There are at least two types of frictional force-sliding and static friction.Though it is not always the case,the friction force often opposes the motion of an object.For example,if a book slides across the surface of a desk,then the desk exerts a friction force in the opposite direction of its motion.Friction results from the two surfaces being pressed together closely,causing intermolecular attractive forces between molecules of different surfaces.As such,friction depends upon the nature of the two surfaces and upon the degree to which they are pressed together

Method of reducing friction:

There are a number of method to reduce friction in which some are discussed here.

Use of Lubricants

The parts of machines which are moving over one another must be properly lubricated by using oils and lubricants of suitable viscosity.

Use of Grease

Proper greasing between the sliding parts of the machines reduces friction.

Use of Ball Bearing

In machines where possible, sliding friction can be replaced by rolling friction by using ball bearings.

Design Modification

Friction can be reduced by changing the design of fast moving objects. The front of vehicles and airplanes made oblong to minimize friction.

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