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Homework Help: Qn on Rotational Kinetic Energy

  1. Mar 31, 2010 #1
    1. The problem statement, all variables and given/known data
    Crab Nebula releases energy at a rate of 5x1031 W, obtaining its energy from the rotational kinetic energy K of a neutron star at its centre.
    Period of neutron star's rotation = 0.0331s. T increases by 4.22 x 10-13s per second.

    What is the moment of inertia of the neutron star?

    2. Relevant equations
    dK/dt = -(4[tex]\pi[/tex]2I/T3) (dT/dt)
    This was the first part of the question which I managed to prove already.
    *Note: the pi is not supposed to be in superscript.

    3. The attempt at a solution
    I equated the power of the star to the above differential equation. Solving for I should be quite easy, but somehow my answer (1.1x 1038) is different from the answer provided (1.1 x 1030).
  2. jcsd
  3. Apr 1, 2010 #2


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    Homework Helper

    Your result looks correct.

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