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Robert Twiss schrieb: > Seems to me a simple dimensional analysis shows the fallacy > of Koenemann's argument: The dimensions of f/A are [M][L][T^(-2)] / > [L^2] and of U are [M][L^2][T^(-2)] / [L^3], so the dimensions of > both quantities are the same: [M]/[L][T^2]. Thus both quantities > scale the same way with the dimension of the system, and Koenemann's > conclusion must be incorrect. The dimensions of a physical term do not tell you which function it follows. This we find from considering boundary conditions or other constraints; this discussion is very much about finding out which are the proper constraints. But if you wish to ignore the divergence theorem and potential theory - well, at the very least you could let me know why you do so; after all, this argument is not new to you. Silence is not an answer. At any given scale you have the choice (a) to consider some given mass with a given surface, then to consider a part of that surface _at constant mass_; in this case f/A holds. Or (b) you consider a smaller mass with a smaller surface which is then the _entire_ surface of the mass; in that case f/A does not hold. In both cases A is a variable, but only in (b) mass is a variable too. And that is all the difference that matters. Falk Koenemann _____________________________________________________________________ | Dr. Falk H. Koenemann Aachen, Germany | | | | Email: [log in to unmask] Phone: *49-241-75885 | | | | URL: http://home.t-online.de/home/peregrine/hp-fkoe.htm | | stress elasticity deformation of solids plasticity strain | |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| | The rain, it raineth on the Just | | And on the Unjust fella. | | But chiefly on the Just because | | The Unjust stole the Just's umbrella. | |_____________________________________________________________________|