Types of Friction

Types of friction

There are three main types of friction in daily life, which include the following:

1. Static friction: an opposing force between two solid object sat rest. In simple words, when there is no relative motion between two solid objects in contact with each other, we describe the frictional force between them a static.
2. Limiting friction: numerically equal to the minimum external force required to make a body just move over another.
3. Dynamic friction: numerically equal to the force of opposition when a body is moving over the rough surface.

Limiting friction

Limiting friction, is equal to the minimum external force required to make a body just move over one another. Is the maximum possible value of static friction. The frictional force must be overcome before an object starts moving. The coefficient of friction will be the same for all masses. The limiting frictional forces is independent of applied force but depends on nature of surface.

Example 1

A block of mass 20 kg is pulled along a horizontal surface. If the coefficient of friction is 0.4, what force is acting on the block?

Solution

Force = coefficient of friction × mass × acceleration due to gravity

F = 0.4 × 20 × 10 = 80 N.