Friction And Types Of Friction The force which prevents the motion of a body over another body and acts in the direction opposite to the movement of the body is known as force of friction (or) simply friction. This force arises mainly due to the roughness and irregularities, which may not be detected by an ordinary touch but viewed under microscope. When a block is placed on another block, a certain degree of interlocking of the minutely projecting particles takes place. This does not involve any force, so long as the block does not move or tends to move. When these blocks tend to move relative to each other, the interlocking property of the projecting particles opposes the motion and rises to a force called friction force.
Force of friction arises due to the relative motion between two parts and hence some energy is wasted in overcoming the friction.
F = µN Where µ = co-efficient of friction N= Normal force of contact
Types of friction.
In general, the friction is of the following two types
- Static friction.
- Dynamic friction.
It is the friction, experienced by a body, when at rest.
Maximum valve of friction is recorded when the body just starts to move by the application of force. The maximum force of friction is known as “limiting friction”. However , when the force applied on the body is lesser than the limiting friction, the body does not move and the force of friction developed in this state is know as “Static friction”.
It is the friction, experienced by a body, When in motion. The dynamic friction is also called Kinetic friction and is less than the static friction. It is of the following three types:
a. Sliding friction
It is the friction, experienced by a body, when it slides over another body.
b. Rolling friction
It is the friction, experienced between the surfaces which has balls or rollers interposed between them.
c. Pivot friction
It is the friction, experienced by a body, due to the motion of rotation as in case of foot step bearings.