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Math Help - need help - spherical coordinates

  1. #1
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    Lightbulb need help - spherical coordinates

    I have really no idea how to define the rho, theta, and phi limits for this question. Please help!!

    Suppose that the density at a point in a gaseous spherical star is modeled by the formula
    delta = deltasub0 times e^ -(rho/R)^3

    where deltasub0 is a positive constant, R is the radius of the star, and rho is the distance from the point to the star's center . Find the mass of the star.
    Last edited by kittycat; September 17th 2007 at 11:58 AM.
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  2. #2
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    You'll need the Jacobian for that. Something about \rho^{2}\sin(\phi) ringing a bell?

    You're just filling up a sphere.

    \rho\;is\;[0,R]

    \theta\;is\;[0,2\pi]

    \phi is -- Oh, you do that one.
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  3. #3
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    Hi TKHunny,

    I have not yet learnt Jacobian.


    Can you only use the idea of spherical coordinates to find the rho, phi, and theta ?


    with the spherical coordinates ideas:
    um, since it is a gaseous SPHERICAL STAR, i guess the theta should be from 0 to 2pi.

    since R is the radius of the star, I guess rho is from 0 to R.

    For phi, I am not sure. I know phi is restricted from 0 to pi.
    I guess phi is from 0 to pi. (purely a guess! )
    If you know the reason , please tell me why. Thank you very much.
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