Question

Friction does not depend on the nature of the surface in contact
(a) true
(b) false

Answer 1

Hint: We can start to answer this question by defining what friction is and from the definition we will get an idea about its dependence with the surface in contact. This will lead us to our required solution.

Complete answer:
Friction or frictional force is a force that opposes the movement of a body when its surface come in contact with another surface.
Factors on which frictional force or friction depends on:
1. Material of the surface: A rough surface creates more frictional force than a smooth surface.
Presence of foreign matter between the surfaces: When there are impurities present on the surface of the material in contact, the nature of it changes. This changes the friction acting on the surface.
2. Area of the surfaces in contact: Area of the surfaces in contact and frictional force are directly proportional, this means that when area increases so does friction.

This all comes back to one thing which is the nature of surface in contact. Hence our statement given in the question is wrong as the surface that comes in contact is one of the few factors that frictional force depends on.

This leads to our required solution which is option (b) false.

Note: Friction can also be determined by another property called the coefficient of friction. When two surfaces come in contact with one another, the coefficient of friction is the ratio of the frictional force resisting motion (the static friction of the body) to the normal pressing the bodies together.