Question

Choose the correct statements. The coefficient of static friction depends upon
(A) The materials of body in contact
(B) quality of matching of the surface in contact
(C) presence of foreign matter between the surfaces
(D) area of the surfaces in contact

Answer 1

Hint
The coefficient of static friction is the friction force between two objects when neither of the objects is moving. And this depends upon the surface of the materials.

Complete step by step answer
As the coefficient of static friction is defined as the frictional force when objects are not moving. For example it prevents the object from sliding through a sloped surface.
The coefficient of friction only depends on the nature of the surfaces. It does not depend on any other factors, including the relative speed of the surfaces and the surface area of contact.
For option (A):
It depends on the surface of the material. you see friction is caused due to interlocking between the surfaces of two materials. since the surface differs for different materials
Option (A) is correct.
For option (B):
As this static friction depends only on the surface of the surface of the material. So it also depends on the quality of matching of the surface in contact.
So option (B) is also correct.
For option (C):
If there is an foreign matter between the surfaces this will also affect the static friction because friction is caused due to interlocking between the surfaces of two materials due to presence of foreign particles the interlocking will also be effective.
So option (C) is also correct.
For option (D):
As static friction does not depend upon the area of the surfaces in contact because it only depends upon the nature of the surfaces of the material.
So option (D) is incorrect.
Hence, options (A), (B), (C) are correct options.

Note
Coefficient of static friction only depends upon the nature of surfaces, it does not depend upon any other factor. Friction is a phenomena which oppose relative motion between two surfaces. If we apply force on the body and it doesn't move, then it is called static friction.