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Homework Help: Satellite & Gravity

  1. Jan 20, 2007 #1
    1. The problem statement, all variables and given/known data

    It is proposed to place a communications satellite in a circular orbit rounf the equator at a height og 3.59 x 10^7m above the earth's surface. Find the period of revolution of the satellite in hours and comment on result.

    Values given:
    Radius of Earth: 6.37 x 10^6m
    Mass of Earth: 5.98 x 10^24kg
    Gravitational Constant: 6.67x10^-11 m^3 kg^-1 s^-2

    2. Relevant equations

    Not sure which one you can you, but i think two different ones have to be used

    3. The attempt at a solution

    This is the only question which i couldn't answer, and when i tried several ways out, it got very far away from result. the answer should be :24 hrs
  2. jcsd
  3. Jan 20, 2007 #2


    User Avatar

    You know that the centripetal accelration is provided by the gravitational force.


    mr(omega)^2 = GMm/r^2

    SO you can calculate omega, the angular velocity.

    Then you should have an equation relating the period tn the angular velocity.
  4. Jan 20, 2007 #3
    thx, i'll try it out. If i get wrong result, i'll post my working to see what's wrong
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