Shielding (sigh, again.) and radiation dose Forum: Spacesettlers
Thread: Shielding (sigh, again.) and radiation dose
# 1537 byrmenich@... on Aug. 10, 2001, 12:09 p.m.
Member since 2021-10-03
It was my impression that either pressure or density was a negative
exponential function of altitude, with 'half-life' of 18,000 feet. It
would seem reasonable to me that pressure would be the integral of the
density. If the density function were exponential, then so too would be
the pressure, because integrals and derivatives of exponentials are
themselves exponential. If any of this is not correct, then please let me
know; thanks.
Ron Menich
"John Wheeler"
Subject: [spacesettlers] Re: Shielding (sigh, again.) and radiation
08/05/01 05:29 dose
AM
Please respond
to
spacesettlers
--- In spacesettlers@y..., rmenich@m... wrote:
>[snip]
> Weight, as I recall, is mass times 'g'. So I don't think you could
at Denver have half the mass of the atmosphere below you. Denver is
not at 18,000 feet. The only way you could have that is if you were
at an altitude where the pressure is half that of sea level.
>
> Educate me, please.
I'll give it a try, but you really need calculus to fully understand.
You are correct about weight. The problem is that gas pressure is not
linear. As you go up, the density of the atmosphere decreases. If
you picture the column of air as a series of balloons with equal
masses of air inside, the ones at the bottom will be made smaller by
the weight of all the balloons on top. At half the pressure, a balloon
will be roughly twice as tall. The other columns around it will
restrict, but not eliminate, expansion in a horizontal plane. This
restriction will increase the pressure in the balloon beyond simply
what is due to the mass of all the balloons above it.
I hope that helps -- I'll probably need to dig out a
physics-with-calculus text to explain better.
--JohnWheeler