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Homework Help: Kinematics - Uniform Circular Motion

  1. Jan 5, 2010 #1
    1. The problem statement, all variables and given/known data
    What is the period, T, of the satellite's orbit (G is the gravitational constant, 6.7 × 10-11 m3 kg-1 s-2) ?
    (The picture is attached)http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys211/oldexams/exam1/sp08/fig18.gif [Broken]

    2. Relevant equations
    a = w^2*r
    F = -Gm1m2/(R^2)

    3. The attempt at a solution

    Using the force equation and "a=F/m",

    I got a = GMe/Rs^2

    And using a = w^2*Rs,

    GMe/Rs^2 = w^2*Rs

    Then, the angular velocity keeps having Rs^3 which doesn't seem to be right when compared to the answer...

    What's wrong with my attempt?
    Please help me out here...

    The answer should be "T= 2*pi*Rs/sqrt(GMe)
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jan 5, 2010 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    No, T should definitely be proportional to R3/2, that's where Kepler's Third Law comes from.
  4. Jan 5, 2010 #3
    Oh, so you think what i was doing was right..?
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