Question

A 100N force is applied on a box, but the box does not move because of the large friction with the ground. Which of the following is correct? (A) The 100N does work on the micro-structure of the box, so the work done is calculated by adding up all the individual movements of the box's atoms. (B) There is no work done because the box does not move. (C) The work done is calculated as if friction was not present. (D) Although the box does not move, the 100N contributes to the Earth's rotation, so work has been done to the Earth-box system as a whole.

Answer 1

Answer: The correct answer is A

Explanation: Let us look at the following experiments. 1) Push an empty box on a smooth floor and then let go. It moves 1 or 2 meters and then stops. The force that stops the box is called force of friction. It is a force that opposes any motion. 2) Put some books (or any objects that have some weight) inside the box and push it again then let go.