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Homework Help: Protostar - Thermal energy change

  1. May 11, 2010 #1
    1. The problem statement, all variables and given/known data

    I have to calculate the change in a protostar's thermal energy [tex]\Delta E_{term}[/tex] on a year.
    I am given the protostar's luminosity [tex]L=3,5\cdot 10^{28}\,W[/tex]
    Furthermore I am told that the energy that the star radiates comes from the lost potential energy under the star's contraction.

    2. Relevant equations
    The virial Theorem: [tex]E_{total}=E_{kin}+E_{pot}=\frac{1}{2}E_{pot}=-E_{kin}[/tex]

    3. The attempt at a solution
    I can calculate the "radiated" (lost) energy: [tex]3,5\cdot 10^{28} W\cdot 365,25\cdot 24\cdot 60^2 \frac{s}{y}=1,105\cdot 10^{36} J[/tex]
    But I don't know how if this is right or how to get to it by arguing from the virial theorem.

    I really hope you can help me.

    Best regards.
  2. jcsd
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