Advantages and Disadvantages of friction Physics Notes
Friction as a necessity (Advantages of friction):
1. Friction help us to walk. When we press the ground with our foot backward, we receive, forward reaction due to friction between the foot and the ground. Had there been no friction, the foot will simply slip away.
2. Friction helps us to write on a blackboard or on paper. As we write, the chalk particles stay on the board due to friction.
3. Friction is necessary for the movement of vehicles on the road. It is the static frictional force which makes the acceleration and retardation of vehicles possible on the road.
4. Friction is helpful in tying knots in the rope and strings.
5. Brakes make use of friction to stop the vehicles. Special high friction materials are used for the brakes of automobiles.
6. Treading of tires of vehicles is done in order to increase friction.
7. The transfer of motion from one part of a machine to the other part through belts and pulleys will not be possible without friction.
8. Cleaning with sandpaper will not be possible without friction.
9. Adhesives will lose their purpose.
Disadvantages of Friction:
- Friction always opposes the relative motion between any two bodies in contact. Therefore, extra energy has to be spent on overcoming friction. This reduces the efficiency of a machine.
- Friction causes wear and tear of the parts of machinery in contact. Thus, their lifetime reduces.
- Frictional forces result in the production of heat, which causes damage to the machinery.
Methods of Reducing Friction:
We can reduce friction:
1. By polishing: Polishing makes the surface smooth by filling space between the depressions and projections present in the surface of the bodies at the microscopic level. Thus interlocking between the body and the surface. Therefore friction reduces.
2. By lubricating: When oil or grease is placed between the two surfaces in contact, it prevents the surface from coming in actual (direct) contact with each other. This converts solid friction into liquid friction which is very small in magnitude. The lubrication reduces friction as well as reduces the heating of moving parts.
3. By proper selection of material: Since friction depends upon the nature of the material used hence it can be largely reduced by proper selection of the material.
4. By converting sliding friction into rolling friction: The friction during rolling becomes much smaller than during sliding of all the frictional forces. The rolling frictional force is minimum. Hence, in order to avoid the wear and tear of machinery, it is required to convert kinetic frictional force into rolling frictional force. The wheels and ball bearings are used to reduce friction as they convert sliding friction into rolling friction.
5. By streamlining: It implies giving a typical shape (sharp in the front) to high-speed vehicles. The fluid friction decreases due to streamlining. It. is for this reason that airplanes, jets, etc are given such typical shapes at the front.
