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Homework Help: Physics question about black holes and determing their mass?

  1. Jul 20, 2015 #1
    1. The problem statement, all variables and given/known data
    a black hole has schwarzschild radius of 15.4km what is the mass of the black hole in terms of the suns mass?

    2. Relevant equations
    Rsch = 2GM/c^2

    3. The attempt at a solution
    I plugged values into the equation and isolated for M and it gave me a different answer. Idk how the suns mass relates to the equation/answer
  2. jcsd
  3. Jul 20, 2015 #2


    Staff: Mentor

    I think they want the ratio so you know the BH mass and you can find the suns mass and then compute the ratio.

    Is it 2 solar masses or 3 or even 1/2... ?
  4. Jul 20, 2015 #3


    User Avatar
    Science Advisor
    Education Advisor

    In astronomy, "one solar mass" is a unit of mass = 1.988435×1030 kilograms. The sun's mass is "one solar mass". For example, the star Arcturus has a mass of 2.3*1030 kg - 1.1 solar masses

    Does that help?
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