Friction and types of friction in detail.dry friction, boundary friction, film friction in detail.
Friction
*it is impossible to produce a perfectly smooth surface. If a block is placed on a surface,interlocking of projecting takes place due to surface roughness of the surfaces.
*when a block tends to move with respect to the mating surface,an opposing force acts in a direction opposite to motion of the block which called as force of friction or simply friction.
*however in some cases ,it is desirable to increase the force of friction for transmission of forces and power
Ex. In mechanisms like belt drives ,friction clutches etc.
Types of friction
Depending upon the surface conditions following types of frictions are considered.
1. Dry friction
2.Boundary friction
3. Film friction
1. Dry friction :-
When friction is experienced between two dry or unlubricated surfaces in contact, it is known as dry or solid friction.
Dry friction is further divided into two types
A. Sliding friction :-
When two dry surfaces have a sliding motion relative to each other ,then it is called as sliding friction ( friction between nut and bolt)
B. Rolling friction :-
When two dry surfaces have a rolling motion relative to each other,then it is called as rolling friction (friction in ball and roller bearing)
2. Boundary friction :-
When friction occurs between two rubbing surfaces having a very thin layer of lubricant between the surface, it is known as boundary friction or non-viscous friction.
3. Film friction:-
When friction is experienced between two rubbing surfaces which are having a thick layer of lubricant between them then it is known as film friction or viscous friction.
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Technology