Q.Explain the advantages and disadvantages of friction.

Friction is a double-edged force: it is essential for many everyday and mechanical actions, but it also wastes energy and damages moving parts — hence engineers work to both use and minimize it depending on the situation.

Advantages of friction:

• Walking and running are possible only because friction between our feet and the ground provides the necessary grip/reaction to push ourselves forward; on a frictionless surface (like ice) we would simply slip.
• Vehicles rely on friction between tyres and the road for both acceleration and braking (traction and stopping).
• Writing with a pen or chalk works because of friction between the writing tip and the paper/board.
• Nails, screws, bolts, and knots stay in place due to friction; without it, they would work loose.
• Belts and pulleys, as in machines, transmit motion through friction between the belt and the pulley surface.
• We can hold and grip objects (like a glass or a rope) only because of friction between our hands and the object.

Disadvantages of friction:

• It causes wear and tear of the moving/rubbing parts of machines (engines, bearings, gears), shortening their working life. …