Explain Friction as necessary evil?
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. It may be thought of as the opposite of "slipperiness".
Friction is the "evil" of all motion. No matter which direction something moves in, friction pulls it the other way. Move something left, friction pulls right. Move something up, friction pulls down. It appears as if nature has given us friction to stop us from moving anything.
There are several types of friction:
1. Kinetic friction :Friction that arises between surfaces in relative motion.
2. Static friction :Friction that acts between surfaces at rest with respect to each other
3. Rolling friction : Friction that occurs when an object rolls over a surface.
Friction is necessary : If there is no friction between any two surfaces in contact, then the present day civilization will be no more- as we cannot even walk properly on the earth. There will be no fabrics and garments, no construction of buildings and no furniture, even no cooking and no vehicles. So friction is necessary. But too much friction causes a heavy loss of energy, wear and tear of machinery. Thus, the efficiency of machines will decrease tremendously. So, it is rightly said that friction is a necessary evil.
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Friction plays an important role in our daily life. FRICTION IS CALLED A NECESSARY EVIL. In some cases friction is useful to us to use and we cnnor do without it. At same yime it is an EVIL in some cases because it results in the loss of energy and wear and tear of the surfaces. We will first describe those cases whre friction is useful to us