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Re: Work/Energy theorem ?



John wrote:
* * *
But seriously, I think you've missed my main point if you are really
distracted by the fact that the train's acceleration relative to the earth
can be turned on and off. All I am saying is that the observer in the
train can make *perfect* sense of the tree's change in KE by invoking the
principle of equivalence. Surely this is a noncontroversial point in the
waning years of the twentieth century. Isn't it?

John
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A. John Mallinckrodt email: mallinckrodt@csupomona.edu
* * *

John,
To say that a gravitational field and an accelerating frame will
produce equivalent effects is certainly a "numerical equality" (to
intentionally harken back to the flavor of a previous discussion).
The question (as with Bernoulli and the W.E theorem) is "what physical
(conceptual) sense (model) are we to make of it?"

I don't think that your train rider is making "perfect sense" out of this.
You have merely given him an alternative calculational algorithm, but he
is at a loss to explain why it works, because these gravitational fields
appear as a magic result of the engineer's actions! I think he can make
better physical (and equivalent calculational) sense by acknowledging his
acceleration!

I am certainly out of my field here, but it seems to me that it was
just such questions which frustrated Einstein as he sought to incorporate
E&M forces into a "unified theory". G.E seems to work fine for purely
gravitational (astronomical) situations; it is a theory of the
gravitational "force"; IMHO its relevance in more general situations
needs work!

This is a field in which I am anxious to learn! If you have physical
answers (not just alternative calculational algorithms) please teach me!

Bob Sciamanda sciamanda@edinboro.edu
Dept of Physics
Edinboro Univ of PA http://www.edinboro.edu/~sciamanda/home.html