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Rotational motion and law of gravity

  1. Apr 13, 2009 #1
    1. The problem statement, all variables and given/known data
    Neutron stars are extremely dense objects that are formed from the remnants of supernova explosions. many rotate very rapidly. suppose that the mass of a certain spherical neutron star is twice the mass of the sun and its radius is 10.0 km. determine the greatest possible angular speed the neutron star can have so that the matter at the its surface on the equator to be just held in orbit by the gravitational force.


    2. Relevant equations



    3. The attempt at a solution
    i no that the gravtiational force must equal the Force
    so GM/r^2=mV^2/ R, but where do i go fom here im lost!!!!!!
     
  2. jcsd
  3. Apr 13, 2009 #2
    ...still lost... idk what to do...
     
  4. Apr 13, 2009 #3
    So the gravitational force must equal the net force? Which is the centripetal force.
    Fg=Fc
    So I think you got this far already, but it looks as though you made a small mistake on this next step when you came up with this equation:
    You may have forgotten to either include a mass term or cross one out.. look at the equations for Fg and Fc again.
     
  5. Apr 14, 2009 #4
    ok ya so i get GMm/r^2=mV^2/R, but still don't know what to do
     
  6. Apr 14, 2009 #5
    What is the question asking us to solve for?

    Do you have everything you need to solve for it? I often make a list of everything that's been given, even before starting.

    R=?
    V=?
    M=?
    m=?
    G=?
     
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