Generally there are four types of friction.
- Static friction
- Sliding friction
- Rolling friction
- Fluid friction
Static: Static friction is the friction between two surfaces that aren’t moving relatively to each other.
When a force is applied to an object, but it does not cause it to move, then static friction works. When a massive body on a floor is pulled by a force but it does not move, then the frictional force created is called force of static friction. The static frictional force is developed opposite to the applied force and acts until motion is produced. When two bodies at rest are in contact with one another and one body is made to move on the other body, the friction produced between them until a relative motion is created is called static friction.
Sliding: Sliding friction is friction where an object slides, or rubs against, another surface.
We fall down and traverse a small distance when we move in a slippery road. When a hard brake is applied on a car moving fast, the car does not stop rather cross a small distance by sliding.
Rolling: Rolling friction is friction between a rolling object and the surface that it is rolling on.
The wheel’s motion of a cycle, motion of marble is example of rolling friction. During travelling we use luggage carrier having wheels to carry goods. If there was no wheel in the luggage carrier then it was too difficult to pull it by sliding from one place to another. Due to the attachment of wheel it becomes easier to pull it i.e. the force of rolling friction is less than that of the static friction.
Fluid: When an object moves in a fluid i.e. a liquid or gas, the friction acts is called fluid friction.
We have to overcome a barrier in water while swimming in the pond. This barrier is the fluid friction. A parachute works by harnessing the air resistance. The air resistance is a type of frictional force which works against the force of gravity of the earth. As an open parachute has a large surface area, it helps provide enough air resistance. As a result, the sky-diver’s falling speed is decreased mostly. So, the skydiver will then be able to descend slowly and safely.
