1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Gas density problem

  1. Feb 20, 2006 #1
    If the exospheric temperature is 1500 K and the hydrogen atom and helium atom densities at 500 km are 1x10^4 cm-3 and 1x10^6 cm-3 respectively, determine at what height the hydrogen atom and helium atom densities will become equal. [Hint: The answer is greater than 3000 km and remember that the acceleration due to gravity g decreases with height]

    wel the densities of the gases in the atmosphere is given by
    [tex] n(z) = n_{0} \exp(\frac{-z}{H}) [/tex]
    where H is the scale height [tex] H = \frac{RT}{Mg(z)}[/tex]

    the densities of H are 10^10 m-1 and He 10^12 m-1
    when the densities are equal
    [tex] 10^{10} \exp\left(\frac{-zg(z)}{1.2 * 10^7}\right) = 10^{12} \exp\left(\frac{-zg(z)}{3.1*10^6}\right) [/tex]
    where [tex] g = \frac{GM}{z^2} [/tex]

    is the setup good so far? Thank you for all your help!
  2. jcsd
  3. Feb 23, 2006 #2
    bump !

    can anyone help?

    i jsut wanna know if the setup is correct or not!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook