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: 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

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Apply the ^3 to everything inside the brackets to which it is attached.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook