Two objects of unequal masses,M and m (M m),are connected by a very light cord passing over an ideal pulley of negligible mass.When released,the system accelerates,and friction is negligible. Which one of the following force diagrams most realistically represents the forces exerted on the two objects in the moving system?

Question

Two objects of unequal masses,M and m (M > m),are connected by a very light cord passing over an ideal pulley of negligible mass.When released,the system accelerates,and friction is negligible.  Which one of the following force diagrams most realistically represents the forces exerted on the two objects in the moving system?

Quizplus · Accepted Answer

Since the masses are unequal and the system is accelerating, there must be a net force acting on the system. In this case, the net force is provided by the difference in tension in the cord on both sides of the pulley. The larger mass, M, experiences a greater tension force than the smaller mass, m. We can see this in the force diagram shown in (C), where the tension force on the left side is greater than the tension force on the right side. Choice (A) and (B) show the same tension on both sides, which would not cause any acceleration in the system. Choice (D) shows a larger force acting on M than on m, but it is not correctly labeled as tension force. Therefore, (C) is the best choice.

Two Objects of Unequal Masses,M and M (M > M),are