Friction can be defined as a resistance force formed from the rubbing between two surfaces. Friction is a form of force that slows down motion and dampens energy. There are two types of friction:
- Static Friction.
- Sliding/Dynamic(moving) Friction.
Static friction is the friction caused between objects that are not moving relative to each other.
Limiting Friction is the maximum value of static friction just before the object begins moving. Therefore it can also be concluded that the value of the required force to just begin moving the object is equal to the Limiting Friction.
Sliding (Dynamic) Friction
Sliding friction is the friction formed between objects that are moving relative to each other. It is important to note that static friction is always greater than sliding/dynamic friction.
Laws of Friction
- The frictional force between two surfaces opposes their relative or attempted motion in other words friction is a resistance force.
- Frictional forces are independent of the area of contact of the surfaces.
- For two surfaces which have no relative motion the limiting frictional force is directly proportional to the normal reaction force.