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Old February 20th 09, 02:12 AM posted to alt.global-warming,sci.geo.meteorology,sci.environment,alt.politics.republicans
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Default Question for theoretical physics about gases

wrote:

It is a most basic fact that objects in a room will all reach the same
temperature as the air in a room.


First Law (if they are passive absorbers and emitters).

So how does the air transfer the energy to the solid substances such
as metal?


Conduction, convection, radiation. Grade school physics.

It is not denied that a piece of metal radiates according to Planck's
Blackbody Radiation Law, which describes the distribution of the
energy of the radiation. The total energy radiated from the surface
conforms with the Boltzman Stefan equation.


At any given wavelength absorptivity exactly equals emissivity - First
Law. Clear and colorless, mirrors, white will be crappy absorbers and
emitters. Porous black surfaces will be near-ideal emitters and
absorbers (e.g., Martin Black; a bolted stack of unused de-greased
double-edged razor blades, sharp sides).

If the air brings the metal to it's temperature at equilibrium, the
metal will be radiating from it's surface the infrared energy
according to the Boltzman Stefan equation, which for 300K, (81F) is
460Wm-2.

[snip crap]

No, stooopid. That is for a blackbody. Colorless diamonds heated to
1000 C (white hot) don't glow - look at their Debye temperature.
Those who know nothing should post in kind.

Hey stooopid - does it make a difference if the surface is an
electrical conductor or an insulator?

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

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Old February 21st 09, 06:23 PM posted to alt.global-warming,sci.geo.meteorology,sci.environment,alt.politics.republicans
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Default Question for theoretical physics about gases

On Feb 20, 3:12 am, Uncle Al wrote:
wrote:

It is a most basic fact that objects in a room will all reach the same
temperature as the air in a room.


First Law (if they are passive absorbers and emitters).


I thought that one was called Zeroth Law. Have I missed something
vital since I retired and went to live in France?


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