What is a Watt???
10-15-2011, 01:09 PM
RE: What is a Watt???
Another idea to try to illustrate what I am getting at here.
Let us have two objects of the same amount, of the same material, at the same temperature.
BUT, the two objects are different shapes, one is a perfect globe, the other an elongated and flattened shape.
Which shape, in a vacuum would cool quicker by radiative emission losses alone?
The answer is presumably the elongated and flattened shape would cool quicker.
But, both objects would (initially) emit IR at the same W/m2 (POWER) ????
So, why would one shape cool quicker than the other?????
I would suggest the answer lies in the difference between the objects in surface area, and therefore the amount emitted at that power......
But, W/m2 does not take amount into account, it is ONLY a power figure.
Such an omission may well "work" for black bodies with no volume, etc, but
it patently CAN NOT work for grey bodies, BECAUSE they have volume...Therefore, for grey bodies amount IS required.
Now will someone please tell me that all the "objects" in the below figure are all the same shape, material, etc, ie assumed to be all perfect black bodies.
BECAUSE, otherwise, as the above illustrates the below plot of global energy flows can not work as depicted.
Richard T Fowler said that the above assumes equilibrium, that is the only way it can work.
But that it seems to me is accepting, without saying, that "everything" in the plot behaves as a black body....ie, all is equal....
I think it assumes "everything" within the plot is a black body, by it's use of W/m2,
which is a far larger and more incorrect assumption that totally destroys the plots basis.
Reality is full of grey bodies, not black bodies. Quite simple really.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.
H. L. Mencken.
The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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RE: What is a Watt??? - Derek - 10-15-2011 01:09 PM
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