A stone hangs by a fine thread from the ceiling, and a section of the same thread dangles from the bottom of the stone (Fig. 4-36). If a person gives a sharp pull on the dangling thread, where is the thread likely to break: below the stone or above it? What if the person gives a slow and steady pull? Explain your answers.
Solution 9Q: We have to understand the behavior of a system consisting of thread and a stone, under the action of sharp pull and slow steady pull. Step 1 of 3 Concept: The tendency of a body to maintain it state of rest or of uniform motion is known as inertia of a body. Step 2 of 3 Under the action of sharp pull: When given a sharp pull to the bottom of the string, there is a sudden application of force. Therefore when a large sudden force is applied to the bottom of the string, the bottom of the string will have a large tension developed in it. Due to the stone's inertia to oppose any sudden action, the upper part of the string will not experience this large force and therefore, the string would break from the part below the stone.