PHYSICS [2 Mark Question Answer]

Force of friction brings about wear and tear in moving bodies. It produces heat and slows down moving body. A lot of energy is wasted in overcoming friction. However, if there were no friction, the bodies will either slip or will not move furthermore, the moving bodies will not stop. Even walking on the surface of earth would have been impossible. Thus, we can say that force of friction is a necessary evil.

Designing a body in such a way that it comes in minimum contact with air or water to ensure that the body experiences minimum frictional force, is called streamlining.
examples of streamlined bodies in nature is Fish.
examples of streamlined bodies in Man-made objects is Aeroplane.

The two ways of minimizing friction between two surfaces are :-
lubricating the surfaces.
Streamlining the body.

The two ways of increasing friction between two surfaces are :-
Making the surfaces rough.
By removing the lubrication between the surfaces in contact.

Two examples where the force of friction is an advantage are :-
t wears out the sole of shoes
It wears out the moving parts of machinery

Two examples where the force of friction is an advantage are :-
• It is used in automobile brakes in order to stop the vehicle
• It helps us to walk on the earth