Two parallel long horizontal bars are placed a distance h apart. The top bar is directly above the bottom one. A thin light string of length L “connects” the bars so that one end of the string can slide freely along the top bar, whereas the other end is glued to the bottom bar. The string is threaded through a small bead of mass m that can slide freely along the string.

Initially, the string is straight, and the bead is held very near the top end of the string, as shown. The bead is then released. Find the speed of the bead at the moment the string breaks. The maximum force of tension that the string can sustain is Tmax=23mg.

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