Re: heat gain problem

In article <1181279217.785509.316600@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
semidemiurge <rick.fetters@xxxxxxxxx> wrote:

Jeffrey, Thank you for the thorough treatment of the thermodynamics
of the problem. I still think there is a difference between
materials.

Yes, I see now where your question was directed, and differences in
materials thermal properties are important to consider in how hot they
"feel" when at the same temperature.

As I pointed out in a different post, I wonder what role thermal
diffusivity plays relative to thermal conductivity to answer this
question (although, for the most part, thermal conductivity and thermal
diffusivity are nearly directly related anyway).

... I think emissivity varies due to chemical
composition, so despite the surface colors appearing very similar
(visual spectrum), maybe they are different at other wavelengths
(infrared, ultraviolet)?

I think emissivities also vary by surface roughness????

Certainly, the energy that a surface absorbs is absorbed across the
entire spectrum of electromagnetic radiation. What we see as "visible"
light is not the entire amount of energy. Therefore, a difference in
chemical composition of the absorber could change its emissivity in a
non-visible wavelength range, causing lower or higher heat absorption
and therefore lower or higher net temperature.

--
JJW
.

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