On Thu, Sep 6, 2012 at 11:29 PM, David Roberson <dlrober...@aol.com> wrote: > 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.
Consider two identical springs. One is uncompressed and other is compressed. Both are at room temperature before being placed in identical cold baths. This tells me the heat content of the spring is unrelated to the energy stored in the compressed spring and the loss of stored energy cannot be explained by a transfer of heat from the spring to the cold bath. > 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. This system converts heat into a store of mechanical energy, whereas the spring system is different because it converts a mechanical force into a store of mechanical energy. > 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. >From the standpoint of CoE all forms of energy equilavent, but the spring example suggests they are not equivalent. harry > -----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 >
