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Surface Gravity of a Neutron Star

  1. Nov 19, 2006 #1
    A neutron star has a mass five times that of Earth and a 10 KM radius. Find the distance from this star's surface a satellite must be at to stay in a circular orbit if the satellite is moving at 50000 km/min.

    First, I changed the 10 KM to meters and found the mass of this neutron star. Then, I changed the 50000 km/min to 833,333 m/s (tell me if this is incorrect). Next, I used the equation v = squareroot GM/R and plugged in (6.67 x 10 to the negative eleventh power) for G and (10 to the 31st power) for M and the radius is unknown. I came up with -10,000 m, which is obviously incorrect. Am i doing something wrong?
  2. jcsd
  3. Nov 19, 2006 #2


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    How did you get 10^31 for M? And what units? g or kg? What unit does the formula require?
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