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Homework Help: Circular Orbit

  1. Oct 15, 2007 #1
    1. The problem statement, all variables and given/known data

    A spy satellite is in circular orbit around Earth. It makes one revolution in 6.00 hours.

    (a) How high above Earth's surface is the satellite?
    ________ km
    (b) What is the satellite's acceleration?
    ________ m/s2

    2. Relevant equations

    GMm/r^2 = m(v^2/r)

    3. The attempt at a solution

    I dont understand how you find these answers if you dont have the mass of the satelite.
  2. jcsd
  3. Oct 16, 2007 #2


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    Homework Helper

    masses cancel...

    GMm/r^2 = m(v^2/r)

    you can cancel m from both sides

    GM/r^2 = v^2/r

    you need to look up M the mass of the earth...

    Get another equation in terms of v and r (use the 6.00hr)

    Then you can solve for r and v, since you have 2 equations with 2 unknowns.
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