1. Types of Friction
1.1. Static Friction
1.1.1. The friction acting between two surfaces which are in contact and placed in rest is called static friction.
1.1.2. It tends to keep the object at rest.
1.1.3. To move an object along the surface, the applied force must be greater than the static friction.
1.1.4. Limiting friction is the maximum fore required to move an object on the surface of another object.
1.2. Sliding Friction
1.2.1. The friction that exists between the two surfaces when they are in contact in which one of them slides on the the surface of another is known as sliding friction.
1.2.2. As the object is moving, their is not enough time for the irregularities to interlock, thus a smaller force is required.
1.2.3. Sliding friction is smaller than static friction.
1.3. Rolling Friction
1.3.1. The friction acting when a object rolls over the surface of another is called rolling friction.
1.3.2. Rolling decreases friction and makes movement of things easier; that is why suitcases and bags are fitted with wheels.
1.4. Fluid friction
1.4.1. The resistance offered by fluids is called fluid friction or drag.
1.4.2. Factors that affect Fluid Friction-
1.4.2.1. Shape of the object.
1.4.2.2. Speed of the object
1.4.2.3. Nature of the fluid
1.4.3. To reduce drag(fluid friction), a body must posses a streamlined shape.
1.4.3.1. Drag due to water
1.4.3.2. Drag due to air
2. Advantagess
2.1. It help us Walk
2.2. Vehicles are able to move on the road due to rolling fliction
2.3. Braking in vehicles
2.4. Friction between paper and pen enables us to write
2.5. Matchsticks lights up due to fiction between head of matchstick and lighting surface
2.6. Helps hammer a nail inside the wall
3. Disadvantages
3.1. Wastage of energy - as additional energy is needed to overcome friction
3.2. Increase in fuel consumption to overcome the energy lost due to friction
3.3. Wear and Tear - soles of shoes, tyres
3.4. Production of unwanted heat - in case of rubbing machine parts
3.5. Production of unnecessary noise
4. Causes of friction
4.1. Irregularities of the Surface
5. Effects of friction
5.1. It Opposes Motion
5.1.1. prevents a stationary object from moving, it also slows down and stops a moving object.
5.2. It results in wear and tear
5.2.1. Surface in contact wear out. Eg.- friction between the tires of a vehicle and road cause the tire to wear away.
5.3. It produces heat
5.3.1. For example, When we rube our hands together
6. Factors Affecting Friction
6.1. Nature of the surface
6.1.1. As a rough surface has more irregularities, the interlocking is more (more friction).
6.2. Weight of an object
6.2.1. A heavy object will press harder on the other object, thus causing greater friction.
6.3. Area of contact
6.3.1. The level of interlocking is entirely dependent on mass of the body.
6.3.1.1. *Note-
6.3.2. Friction is independent of contact area.
7. Reducing friction
7.1. Using Lubricants
7.2. Using Soap Solutions
7.3. Using Ball Bearings
7.4. Polishing Surfaces
7.5. Improving design
8. Increasing friction
8.1. Sometimes its desirable to increase friction, for eg
8.1.1. Tyres or vehicles have deep groves called treads
8.1.2. Weight lifters apply powder
8.1.3. Athletes and mountaineers have spikes on the soles of their shoes
8.1.4. Sand is spread to increase friction after a oil spill or rain
8.1.5. Grinding stone has rough surface to to provide friction for grinding
8.1.6. Handles of cricket bats and bicycles are covered with rubber grips to get a firm grip
8.1.7. Screws provide more friction as compared to nails as they have threads around them
8.1.8. Tiles used on the floors of a bathroom are designed with small grooves or gentle spikes on the surface - this helps increase friction in-between the surface of the wet floor and our foot