# Types Of Friction

## Static Friction

Static Friction is friction between two or more solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface. The coefficient of static friction, typically denoted as μs, is usually higher than the coefficient of kinetic friction.

## Fluid Friction

Fluid friction occurs between layers within a fluid that are moving relative to each other. This internal resistance to flow is described as viscosity. In everyday terms viscosity of a fluid is said to have "thickness".

## Ex. Fluid Friction

Examples of fluid friction include hailstones falling from the atmosphere, the drag of air on an airplane, water slowing the speed of a boat, air slowing a bullet and fish swimming underwater.

## Rolling Friction

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface.

## Kinetic Friction

Static friction is friction between two or more solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface. The coefficient of static friction, typically denoted as μs, is usually higher than the coefficient of kinetic friction.

## Ex. Kinetic Friction

Friction between a car’s windshield and the air as you drive into the wind. Friction between your shoes and the ground when you stand still.