On Thu, Jun 8, 2017 at 1:42 AM, H LV <hveeder...@gmail.com> wrote: > > On Jun 7, 2017 10:06 AM, "Jed Rothwell" <jedrothw...@gmail.com> wrote: > > > > H LV <hveeder...@gmail.com> wrote: > > > >> > >> Joule's apparatus used a spindle with paddles which was turned by a > falling weight outside the calorimeter. The motion of the falling weight > did not result in the generation of potential energy. > > > > > > That was a different experiment. I was referring to one in which he > wound a spring inside a calorimeter. > > > > - Jed > > > > The passage you cite mentions that Joule is concerned that when a spring > is wound it does not produce heat. If a gas behaved like a spring in > addition to heating up when compressed then it would be incorrect to infer > the heat energy of the gas from its temperature. > > Harry > Developing this idea further...
Take gas Z and apply some special treatment to it and call it gas Z*. Perform some mechanical work on gas Z* by compressing. it. As expected the temperature of gas Z* rises with the compression, but curiously the temperature sometimes rises again long after the compression has occurred. One approach to explaining this behaviour is to hypothesize that gas Z* consists of a difficult to understand structure which is capable of storing energy from compression and then releasing it at a later time under circumstances which are poorly understood. As a test of the hypothesis, the same mechanical work is performed on the untreated gas Z in the hope that it will exhibit a greater temperature rise under compression which would indicate that gas Z* stored energy during compression. Unfortunately the test reveals no difference so it appears the storage hypothesis is untenable. However, this interpretation rests on the assumption that the gases should differ in their capacity to store energy. On the other hand, there is another valid interpretation which says both gases store energy but only the treated gas has the capacity to release of energy. Harry
