Re: Work/Energy theorem ?

[John Mallinckrodt <ajmallinckro@CSUPomona.Edu>]

On Fri, 4 Apr 1997 SCIAMANDA@edinboro.edu wrote:

>       What is the train rider to make of the coincidence that these 
> gravitational fields always appear when (and only when) the engineer 
> applies the brakes or the accelerator?

The same general kind of thing that you or I make of the coincidence that
what we mistakenly (but very usefully!) call a "gravitational field" 
appears only when we resist the local orders of space-time to behave
inertially, (i.e., to fall) by allowing ourselves to be supported by
something!

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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