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Homework Help: Deriving the enclosed Mass

  1. Oct 27, 2011 #1
    1. The problem statement, all variables and given/known data
    A popular model for the mass distribution in a spheroid (such as a bulge) is the
    Hernquist model, with density

    ρ(r) = M(total)*a / 2πr(a+r)^3

    M(total) is the total mass. a is constant with dimensions of length. Derive the enclosed mass

    3. The attempt at a solution
    I am completely unsure on how to go about doing this? Any help is appreciated!
  2. jcsd
  3. Oct 27, 2011 #2


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    Science Advisor
    Homework Helper

    How are generally mass density and mass related ? (Hint: integral).
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