Lets think about the heated bar from another point of view. Instead of heating the bar first, lets compress it so that the length is reduced. We could place it inside a press and force it to store energy inside just as a normal spring would. Work must be performed upon the metal as it is compressed and this work would be stored in the form of potential energy.
Now, it the bar is placed within a cold bath as with the spring, the compression can be slowly released until the bar relaxes. All of the potential energy disappears as far as our observations are concerned but we know that heating of the bar will bring it back to its original value. In my opinion this is exactly comparable to the original spring compression experiment. So, heat is removed from the bar and the potential energy becomes less. Why is this not the same? Dave -----Original Message----- From: Harry Veeder <hveeder...@gmail.com> To: vortex-l <vortex-l@eskimo.com> Sent: Fri, Sep 7, 2012 1:16 pm Subject: Re: [Vo]:Compressed spring - what happens to the stored energy at different temperatures? snip... > 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, hereas the spring system is different because it converts a echanical force into store of mechanical energy. rom the standpoint of CoE all forms of energy equilavent, but the pring example suggests hey are not equivalent. harry ... snip
