On Fri, Sep 7, 2012 at 8:35 PM, David Roberson <dlrober...@aol.com> wrote: > 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
Dave, see my recent posts to Abd and Jouni. Abd was right that the length of the spring is not relevant. However, instead of potential energy being destroyed, I now think the opposite is possible. Potential energy can be created by placing the compressed spring in the cold bath. Instead of compressing the spring with weight imagine compressing it and then inserting the spring inside a box to maintain the compression. When that system is submerged in the cold bath, the spring will become stiffer and this will translate into more pressure on the ends of the box, and therefore more potential energy. harry > -----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, > whereas the spring system is different because it converts a > mechanical force into > a store of mechanical energy. > > > From the standpoint of CoE all forms of energy equilavent, but the > spring example suggests > they are not equivalent. > > harry > .... snip
