I think that the spring will return to its original position as in the first case if the temperature is returned to the same as before. This situation would demonstrate that the missing energy is taken away as heat into the liquid nitrogen so it does not disappear.
You could get results of the opposite nature if you place a metal bar between two firmly attached uprights and apply heat. The heated bar would expand and push apart the uprights, but the extension force would go away once the bar is cooled back to room temperature. COE is conserved in both of these experiments. You must search carefully for energy sources and sinks since sometimes they are difficult to locate. In the heated bar case you can see that heat energy is added to the device which results in expansion. The force due to the expansion does work by moving the uprights apart and is returned when the heat energy is extracted by cooling. Dave -----Original Message----- From: Harry Veeder <hveeder...@gmail.com> To: vortex-l <vortex-l@eskimo.com> Sent: Thu, Sep 6, 2012 10:25 pm Subject: [Vo]:Compressed spring - what happens to the stored energy at different temperatures? If a spring is compressed by a force at room temperature, the spring will return to its original length once the force is removed. In the language of CoE the compressed spring is said to "store" the energy of the work done by the force. Now compress the spring again and then place it in a bath of liquid nitrogen. The spring will not return to its original length once the force is removed. At this stage I would say some of the "stored energy" has vanished and CoE has been violated. Harry
