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Homework Help: Hydrostatic equilibrium

  1. Mar 13, 2006 #1

    So, I've been given that archimedes principal for an atmospheric layer of gas on a planet is
    dP/dr = -rho*g
    where g is constant.

    For a vanderwaals gas,
    P = rhot*R*T - a*rho^2

    I used the quadratic formula & solved for rho and put that into the dP/dr equation. getting...

    dP = [((-RT +/- ((RT)^2 - 4aP)^.5) / 2a ] dr

    now i need to separate the variables and integrate, to get P as a function of r, but how do i get P out of the right side of the equation???

  2. jcsd
  3. Mar 13, 2006 #2


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    Don't you need an equation for T?
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