Question

Friction does not depend on the nature of the surface in contact.
A. True
B. False

Answer 1

Hint:One should recall the concept of cause of friction and its dependence factors to solve this question. The smoother the surface, lesser the interlocking between the two surfaces, the lesser the fiction between the surfaces in contact.

Complete answer:
 When two surfaces are in contact the frictional force acts to prevent the relative motion between the two surfaces. When the applied force is greater than the frictional force between the two surfaces the body can move relative to the surface.
We know that frictional force is given as \[f = \mu N\]. ---------(1)
Where $f$ is the frictional force, $\mu $ is the coefficient of friction and $N$ is the normal force acting between the two surfaces in contact.
If the surface in contact is smooth the value of coefficient of friction is less. The value of coefficient of friction increases with the increase in roughness of the two surfaces. Equation 1 shows that friction is directly proportional to the coefficient of friction. Therefore changes with the change in the coefficient of friction.So friction depends on the nature of surfaces in contact.Thus, the statement is false as friction depends on the nature of the surface in contact.

Hence, option B is the correct answer.

Note: Students should know the factors on which friction depends correctly to solve this question. Frictional force depends on the nature of the surfaces in contact and increases with the increase in the roughness of the surface. Friction is due to interlocking between the molecules of the surfaces as no surface is perfectly smooth. If the surface is rough the interlocking becomes stronger thus increases the friction between the two surfaces.