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I have heard many people tell me that the tensional force is bi-directional. Consider the following case where a (mass-less) rope is used to transmit tension.
The rope is being pulled (by hand) with a force of 5 newtons. Thus the mass (along with the rope) will have an acceleration of 5 ms^(-2). (Neglect friction)
1) Considering a point P on the rope, have I represented the tensional force on the rope correctly?
2) By Newton's Third Law, if the rope is pulling on the block, the block must exert an equal and opposite force on the rope. So, shouldn't the body not have any motion? A similar question was asked here: With Newton's third law, why are things capable of moving?. According to the answer provided, it is the force of the muscles that is responsible for the resulting acceleration.
So then what force is transmitted across the rope? It has to be the force of the muscles and not any other force since the tension in the rope is 5 newtons. But if it is so, the force exerted by the block on the rope (reaction) should also be 5 newtons. This means that the object will have no motion! Am I misunderstanding something here?