Can an object exert a force on itself? Argue for your answer?
No, it can’t. If it could, objects would spontaneously accelerate and the world’s energy problem would have been solved a long time ago.
If object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A.
Let’s assume an object exerts a force on itself. According to Newton’s third law of motion, the object eventually has to create a reaction force which would terminate the action force such that the total momentum stays zero and the object would still Newton’s third law of motion:not move.
Thus, for this case of spontaneously accelerating objects, Newton’s law must be invalid.
Question: A flat cushion of mass is released from rest at the corner of the roof of a building, at height . A wind blowing along the side of the building exerts a constant horizontal force of magnitude on the cushion as it drops as shown in Figure P5.91. The air exerts no vertical force. (a) Show that the path of the cushion is a straight line. (b) Does the cushion fall with constant velocity? Explain. (c) If , , and , how far from the building will the cushion hit the level ground? What If? (d) If the cushion is thrown downward with a nonzero speed at the top of the building, what will be the shape of its trajectory? Explain.
Question: . An iron bolt of mass hangs from a string long. The top end of the string is fixed. Without touching it, a magnet attracts the bolt so that it remains stationary, but is displaced horizontally to the right from the previously vertical line of the string. The magnet is located to the right of the bolt and on the same vertical level as the bolt in the final configuration. (a) Draw a free-body diagram of the bolt. (b) Find the tension in the string. (c) Find the magnetic force on the bolt.
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