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Homework Help: Densities of 3 Stars

  1. Mar 21, 2005 #1
    Alright, I just need to find the density of three stars in g/cm^3.

    I have been given the following information:

    Density of a star = Mass / ((4/3)*pi*Radius^3)

    First star is a white dwarf:
    Mass = 2 * 10^30 kg
    Radius = 5000 km

    Second star is a neutron star:
    Mass = 2(2 * 10^30) kg
    Radius = 20 km

    Third is a black hole:
    Mass = 5(2 * 10^30 kg)
    Radius = 5 km

    This is what I did for each:
    Convert the mass to grams and convert radius to cm. So...

    1. 2 * 10^30 = 2 * 10^33 cm and 5000 km = 500,000,000 cm.
    (2*10^33 grams)/((4/3)*pi*(500000000)^3 cm^3)
    Density = 3,819,718.63 g/cm^3

    Did I do that first one right?
     
  2. jcsd
  3. Mar 21, 2005 #2
    Looks ok to me, except in your first line you mean 2 x 10^33 g, not cm.
     
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