Richard Clark wrote:
On Fri, 03 Dec 2004 16:13:44 -0600, Cecil Moore
wrote:
ExH traveling in one direction is positive.
Radiation
ExH traveling in the opposite direction is negative.
Rearadiation
You got transmitters in Texas that suck?
Maybe so. Texas certainly does seem to have its own unique set of
physical laws. ;-)
"Physicists say no work is done if the starting line and the finish
line are the same for a marathon."
:-)
No physicist I know would ever say something like that. Only a gross
misapplication of Newtonian mechanics and/or thermodynamics could lead
someone to such a belief. For example, such a person might think that a
ball thrown up into the air has had zero work performed on it after it
returns to the hand which threw it. The fact is, it requires as much
work to return it to the earth as it does to throw it into the air.
(There are some interesting physics demonstrations on how this doubling
of work can be used to interesting advantage.) But since in mechanics
there is no such thing as negative work, total work is accumulative.
Potential and kinetic energies are of course restored to initial
conditions, but the conversion from one to the other does not ordinarily
occur without some form of external 'help'. The misunderstanding is at
least consistent with some similar misunderstandings that have been
expressed with regard to the physics of power and energy.
ac6xg
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