Question

why we have to reduce friction in some cases?​

Answer 1

Explanation:

Friction between the surface of the road and tyres of our vehicles allow the vehicles to move without slipping. Friction produces heat causing wastage of energy in machines. Friction causes wear and tear of moving parts of machinery, soles of shoes, etc.

Answer 2

Answer:

Objects moving through fluids such as air or water also encounter frictional forces which reduce their motion. This is known as drag. Friction prevents objects from moving or slows them down. It also causes wear on surfaces as they rub against each other and generates heat.