Question

In which of the following cases is ground applying frictional force on the object?
Situation I- When an object is kept on a plain rough horizontal ground
Situation II- While you are trying very hard to push an object but it moves very slowly
(A) Only I
(B) Only II
(C) Both I and II
(D) Neither I nor II​

Answer 1

Answer:

(B) Only II

Explanation:

Friction arises in part because of the roughness of the surfaces in contact, as seen in the expanded view. In order for the object to move, it must rise to where the peaks can skip along the bottom surface. Thus a force is required just to set the object in motion.