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Homework Help: Angular Velocity of a neutron start

  1. Oct 21, 2008 #1
    1. The problem statement, all variables and given/known data

    Supposed that the mass of certain spherical neutron star is twice the mass of the sun (1.991*10^30) and its radius is 13.5 km. Determine the greatest possible angular speed it can have so that the matter at the surface of the star on its equator is just held in orbit by the gravitational force?
    The answer is in the range of 5000-20000 radians/sec

    2. Relevant equations


    3. The attempt at a solution

    I used the escape speed equation. I plugged in the mass of the star times G, divided by the radius of the star (13.5km or 13500 m) and then solved for Vesc. But I'm not really sure that's what I am really looking for. I think I might be approaching the problem wrong, but I'm not sure where to go from here.
  2. jcsd
  3. Oct 21, 2008 #2


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    Consider a tiny piece of matter at the surface and assume that its acceleration in the radial direction is 0. This means that the gravitational force is equal to...what?
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