# Types of Friction in Engineering Mechanics

## Friction in Engineering Mechanics:

It has been established for a long that all surfaces of the bodies are never perfectly smooth. It has been observed that whenever even a very smooth surface is viewed under a microscope, it is found to have some roughness and irregularities, which may not be detected by an ordinary touch.

It will be interesting to know that if a block of one substance is placed over the level surface of the same or different material, 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. But whenever one of the blocks moves or tends or moves tangentially with respect to the surface, on which it rests, the interlocking property of the projecting particles opposes the motion. This opposing force which acts in the opposite direction of the movement of the block is called friction.

## Types of Friction:

Friction is mainly two types:

• Static Friction
• Dynamic Friction

### Static Friction:

It is the friction experienced by a body when it is at rest. In other words, it is the friction when the body tends to move.

### Dynamic Friction:

It is the friction experienced by a body when it is motion. It is also called kinetic friction. The dynamic friction is of the following two types:

1. Sliding Friction: It is the friction experienced by a body when it slides over another body.

2. Rolling Friction: It is the friction experienced by a body when it rolls over another body.