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Homework Help: More Gravitation

  1. Apr 15, 2010 #1
    1. The problem statement, all variables and given/known data
    It is possible to put a satellite into an orbit so that it stays in a fixed position over a point on the Earth's equator (a geostationary or geosynchronous satellite).
    a) What would the be height of such a satellite above the Earth's surface?
    b) Why must such a satellite orbit above the equator?
    c) What are the uses of such a satellite, as compared to lower orbit satellites?

    2. Relevant equations

    3. The attempt at a solution
    a) Kepler's Third Law?
    b) Fatest Velocity?
    c) No Idea :D
  2. jcsd
  3. Apr 15, 2010 #2


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    Hi ride4life! :smile:
    Forget Kepler (this is the second time, isn't it?) … there's hardly any exam questions on Kepler :wink:

    a) use Newton's second law and Newton's law of gravitation (remember, you want T = 24*3600)

    b) what shape would the orbit be if it wasn't on the equator?

    c) google or wiki for "geostationary" :smile:
  4. Apr 15, 2010 #3
    a) i used kepler's third law with
    r=h+6.4x106, with h being the distance from the earth's surface to the satellite
    ended getting 3.59x108m
    b) orbit above the equator would be a circle, elsewhere it would be an ellipse?
    c) geostationary satellites move at the same speed as the earth, allowing transmitters to maintain links for periods of time, such as radio
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