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Homework Help: How long will the sun shine for? (relativistic energy)

  1. Sep 11, 2012 #1


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    Gold Member

    1. The problem statement, all variables and given/known data

    The sun radiates about 4.0E26 J/s.

    a) How much mass is released as radiation each second?

    b) If the mass of the sun is 2.0E30 kg, how long can the sun survive if the energy release continues at its present rate?

    2. Relevant equations

    Not sure, but I think I'm supposed to use


    3. The attempt at a solution


    Δm = ΔE/c2
    Δm = 4.0E26/c2 = 4.44E9 kg/s


    2.0E30 kg x (1 s / 4.44E9 kg) =

    4.5E20 seconds or
    1.42E13 years

    Is this correct?
  2. jcsd
  3. Sep 11, 2012 #2
    Yep, I think that's right.
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