Friction is a force that can be both helpful and harmful depending on the situation.
That’s why it is called a “necessary evil.”

Why Friction is an Evil (Harmful)

1. Causes Wear and Tear

Friction wears out the surfaces of machines, shoes, tyres, and tools.
The rubbing of surfaces damages them over time.

2. Produces Unwanted Heat

When two surfaces rub, heat is produced.
This heat can damage machine parts and needs cooling (like engines).

3. Wastes Energy

Extra energy is needed to overcome friction.
This increases fuel consumption in vehicles and electricity use in machines.

4. Reduces Efficiency of Machines

Friction slows down moving parts, making machines less efficient.
They need more power to run smoothly.

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Why Friction is Necessary (Useful)

1. Helps in Walking

We can walk only because friction gives grip between our feet and the ground.
Without friction, we would slip.

2. Helps Vehicles Run

Tyres grip the road because of friction.
Without friction, vehicles cannot start, stop, or turn safely.

3. Helps in Writing, Gripping, and Holding Things

Pens and pencils write because of friction.
We hold books, bags, or bottles because friction gives us grip.

4. Helps in Braking and Control

Brakes work due to friction between the brake pad and the wheel.
Friction helps us control speed and stop safely.

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Why Friction Cannot Be Eliminated

1. Surfaces Always Have Irregularities

Even smooth-looking surfaces have tiny bumps.
These bumps interlock and create friction.

2. Some Friction is Always Needed in Daily Life

We cannot walk, write, hold objects, or drive vehicles without friction.
So friction can be reduced, but never completely removed.