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Figure (5-Q4) shows a heavy block kept on a frictionless surface and being pulled by two ropes of equal mass m. At t = 0, the force on the left rope is withdrawn but the force on the right end continues to act. Let F1 and F2 be the magnitudes of the forces by the right rope and the left rope on the block respectively.(a) F1 = F2 = F for t < 0(b) F1 = F2 = F + mg for t < 0(c) F1 = F2, F2 = F for t> 0(d) F1 < F2, F2 = F for t > 0. |
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Answer» (a)F1 = F2 = F for t < 0. Explanation: (a) is correct because as seen in the figure for t<0, F1 = F2 =F. For the same reason (b) is incorrect. Since at t=0 the force on the left rope is withdrawn so at t>0, F1 ≠ F, F2 ≠ F. So (c) is in correct. Since force on the left rope is withdrawn at t=0, so at t>0 force by the right rope on the block will not change ie. F1 will not be less than F. So (d) is incorrect. |
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