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I tied a springy stick into a knot, giving it potential energy, because it could spring out of the knot shape. But then I threw it into a fire and it burned to ash without untying. What happened to the potential energy?

Asking on behalf of /u/HomeWasGood on Reddit.

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    $\begingroup$ Does this answer your question? What happens to the potential energy of a compressed spring when it dissolves in acid? $\endgroup$
    – knzhou
    Apr 28, 2020 at 1:35
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    $\begingroup$ I disagree that the answer for this is the same as for a spring. I expect the energy ultimately winds up as heat, but the mechanism is different. Wet wood is springy. Dry wood is not. Wood dries as it burns. Wet wood left in a knot relaxes. If you untie it later, it will curl back up. Heated wood undergoes a phase transition from a solid stiff phase to a solid rubbery phase. This is much like the phase transition that makes it possible to iron clothes. $\endgroup$
    – mmesser314
    Apr 28, 2020 at 2:48

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