Question

Friction is a necessary evil explained with examples.

Answer 1

Hint: Friction is a contact force along the tangent to the contacting the surfaces to destroy the relative motion between them. Friction is very necessary in our lives. Since the friction tries to destroy the motion of the body it can cause some evil effect on the body. Apply this logic to prove your point friction is a necessary evil.

Complete step by step solution:
Friction is the opposing force which comes between two surfaces so as to impede the relative motion between them. Friction is regarded as an electromagnetic force. Friction can also be due to the cohesive or adhesive force among molecules at close proximities.

Friction can be a necessary evil because it is useful in our day to day life as well as harmful. We can walk, write, hold things, and lift objects due to friction. Hence it is necessary in our lives. Many processes cannot be done without friction. But it is also unnecessary at times. It results in energy loss, wear and tear of parts of machines.

Friction results in the large amount of power loss in engines and it brings down their efficiency. Machines consume more energy due to friction. But machine parts like conveyor belts, engine need friction. The wear and tear of the machine increases due to friction. Friction can also wear and tear in our shoes. But we can walk and run due to friction.

Friction causes unnecessary heating of parts of the machinery which can alter its working condition. Unwanted fires are caused by friction. But friction also helps to light a matchstick.
Hence, we can say friction is a necessary evil.

Note: The surfaces in contact will slip on each other without opposition in the absence of friction. This may be producing a dangerous motion. Polishing, using lubricants, using ball bearing, streamlining can reduce friction. Another effective way to reduce friction is to place a thin cushion of air maintained between the solid surfaces in relative motion.