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Question about supernova kinetic energy

  1. Jun 18, 2012 #1

    lr1

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    A9: Supernova Remnants
    Consider a supernova explosion in the outer 4M⊙ of a dying star, ejected at a speed of 5000 km/s.
    a ◮ What is the kinetic energy of the expanding ejecta?
    b ◮ The ejecta are slowed by sweeping up the local interstellar gas. Assuming the density of the interstellar gas
    is ig = 2 × 10−19 kg/m3, how large a volume will be swept up by the time the outflow velocity has decreased
    to 10 km/s? HINT: Assume the KE of the expansion is conserved.
    A10:
     
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  3. Jun 18, 2012 #2

    tiny-tim

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    welcome to pf!

    hi lr1! welcome to pf! :smile:

    (try using the X2 button just above the Reply box :wink:)

    show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
     
  4. Jun 18, 2012 #3

    lr1

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    Part a I used virial theorem for kinetic energy 3mv^2 and for part b I used mass= density / volume but am confused with swept volume
     
  5. Jun 19, 2012 #4

    Chronos

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    Virial theorem is only useful on large scales, for a region near a supernova event you still need to use kinematical models.
     
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