February 23rd 09, 09:55 PM
posted to sci.environment,sci.physics,alt.culture.alaska,sci.geo.meteorology
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First recorded activity by Weather-Banter: Feb 2009
Posts: 12
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Power density of the Sun
"bw" wrote in message
...
"kiloVolts" mantrap@4u3t7s0s5A6s1e7F3G6rH3h5d4q3a3s2aX7A2D5y6 j1z.com
wrote in message ...
Dimensional analysis yields an understanding of the power density of the
Sun. All of the power generated within the Sun is radiated from the
photosphere, whose area scales as the radius of the Sun, which scales as
4*Pi*R^2 while the volume scales as 4/3*Pi*R^3. Hence, the power density
of the Sun per unit volume or per unit mass, scales as 3/R. From a human
perspective, since the radius of the Sun R, is almost infinite, the power
density per unit mass is infinitesimal. In fact, when the Sun is active,
the power density of the Sun is less than that of the human body:
http://en.wikipedia.org/wiki/Sun
The power density of the Sun per unit mass could go from infinitesimal of
zero and we would not notice, because we are mortal.
a) Solar power is 3.8 E26 watts.
b) surface area is 6.1 E18 square meters.
a/b is 62 E6 watts per square meter, thats 62 megawatts per square meter.
Adult human has around 1 square meter of surface area, therefore about 100
watts per square meter.
Duh.
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