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Homework Help: Finding mass of black hole once given the density

  1. May 2, 2012 #1
    1. The problem statement, all variables and given/known data
    Calculate the mass and radius of a black hole with density 750 kg/m^3.

    2. Relevant equations

    3. The attempt at a solution
    In a previous question, I already used the Schwarzchild radius to come up with a formula for the density of a black hole:
    D = (mass/(4/3pi((2Gmass/c^2)^3). I realize that this should be enough to solve for mass, but I am having difficulty with the algebra...How do I solve for mass when one of the "mass" variables is stuck inside the Scharzchild radius in a complicated fraction?
  2. jcsd
  3. May 2, 2012 #2

    George Jones

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    Staff Emeritus
    Science Advisor
    Gold Member

    Apply the ^3 to everything inside the brackets to which it is attached.
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