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Message No. 6 posted by canucme on 12/21/99 15:55 PST
This is a reply to message No. 5
 Current Topic:radiation teaser To mimic a bald head exposed to the cold night sky, try these values: Object 1 (Bald Head) Temp:  95 deg F Area:  0.3 ft^2 (a reasonable guess) Emissivity:  0.9 (another reasonable guess) Object 2 (night sky) Temp:  -150 deg F Area:   anything much larger than the area of object 1 Emissivity:  1 (sky acts like a blackbody) ViewFactor:  1  (assume that the head sees nothing but sky) This will give a heat loss of almost 12 watts, a reasonable estimate for this problem.  The earlier suggestion of 20 watts was probably an overestimate; object 1's area was chosen too large.
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 canucme, Why is the night sky -150F? I have a co-worker who insists, de... No. 20, Posted by quiche on 01/06/00, 16:25 PST. Thanks for your response. I think i understand the example much better now... No. 13, Posted by daffodil on 01/05/00, 09:03 PST.