Question

The coefficient of static friction between two surfaces depend on
(A) The nature of the surface
(B) The shape of the surface in contact
(C) The area of contact
(D) all of the above

Answer 1

Hint: The frictional force is the force applied by the surface on the object to move across it. Static friction is the frictional force that exists between the stationary object and the surface on which the object is resting.

Complete answer:
We know that the coefficient of static friction is also equal to the tangent of the angle of the friction.
The magnitude of the limiting (maximum) static frictional force depends upon the nature of the surfaces in contact and on their roughness. It is independent of the size or area of the surfaces.

$\therefore$ The coefficient of static friction between two surfaces depends on the nature of surfaces. Hence, option (A) is the correct option.

Additional information:
The coefficient of static friction is represented by ${\mu }_s$.
The coefficient of friction (µ) is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together.
The coefficient of friction is material dependent. For example, ice on steel has a low coefficient of friction, while rubber on the pavement has a high coefficient of friction.
Coefficients of friction value are in the range of near-zero to more than zero.
The coefficient of static friction exhibited by a pair of contacting surfaces depends upon the combined effects of material deformation characteristics and surface roughness, both of which arise in the chemical bonding between atoms in each of the bulk materials and between the material surfaces and any adsorbed material.

Note:
Surface friction arises due to the surface roughness of metal surfaces called Asperities. it plays an important role in determining the magnitude of the static friction.