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Density of the sun as a white dwarf.

  1. Jul 7, 2009 #1
    1. The problem statement, all variables and given/known data

    In about 5 billion years, at the end of its lifetime, our sun will end up as a white dwarf, having about the same mass as it does now, but reduced to about 15,000 km in diameter.What will be its density at that stage?

    g/cm^3

    2. Relevant equations

    D=m/v
    4/3(3.14)r^3

    3. The attempt at a solution

    Sun's mass is Sun's mass is = 1.99 x 10^30 kg
    kg to g = 1.99 x 10^33
    v = 7500 km to 750,000,000 centimeter

    D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^33)^3 = 1.12 x 10^54 ???

    Is this correct? I have been getting it wrong each time I input the answer
     
  2. jcsd
  3. Jul 7, 2009 #2

    negitron

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    Look at what you put for the radius in your equation.
     
  4. Jul 7, 2009 #3
    D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^9)^3 = 2.09 x 10^11?
     
  5. Jul 7, 2009 #4

    negitron

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    You're off by a factor of 10 somewhere. Careful of your exponents.
     
  6. Jul 7, 2009 #5
    D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^8)^3 = 6.338 x 10^23
    Seems to be wrong.
     
  7. Jul 7, 2009 #6

    negitron

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    Your equation is correct. Take it one step at a time.
     
  8. Jul 8, 2009 #7

    Redbelly98

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    Agreed. What is the volume? Then take the ratio mass/volume.
     
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