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This question does a good job explaining why tension is the same. However, I don't understand the part when he says:

"This upward movement would relax the tension in the upper part of the rope ($T_t$ decreases) and increase the tension in the lower part of the rope ($T_b$ increases). This will continue until $T_t$ equals $T_b$ and there is no net force on the rope".

Why does the movement of the rope segment, altering its location, have an affect on the Tb and Tt. Shouldn't the two tensions be constant no matter where they are in the system. Why does Tt moving up lower/relax its tension? And why does Tb moving up increase its tension.


marked as duplicate by Qmechanic Feb 19 '17 at 0:10

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  • $\begingroup$ I fixed that and the missing quotation markup, and replaced that hacky html subscritps with MathJax. $\endgroup$ – dmckee Feb 18 '17 at 22:48
  • $\begingroup$ Related: physics.stackexchange.com/q/308011 $\endgroup$ – dmckee Feb 18 '17 at 22:49
  • $\begingroup$ It should be an enough argument that $T_t-T_b=ma=0$ thus $T_t=T_b$ $\endgroup$ – user126422 Feb 18 '17 at 22:59
  • $\begingroup$ I'd appreciate something more in depth and related to my question. $\endgroup$ – A.AK Feb 18 '17 at 23:01
  • $\begingroup$ Related: physics.stackexchange.com/q/156413/2451 and links therein. $\endgroup$ – Qmechanic Feb 18 '17 at 23:19