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Homework Help: Kepler's Third Law satellite problem

  1. Feb 20, 2010 #1
    1. The problem statement, all variables and given/known data

    An orbiting satellite stays over a certain spot on the equator of (rotating) Pluto. What is the altitude (in km) of the orbit (called a "synchronous orbit")?

    2. Relevant equations
    r = [(G*M*T^2)/4pi^2]^(1/3)
    h= r-radius of pluto

    3. The attempt at a solution
    I have plugged in the numbers (6.67e^-11) for G, (1.31e^22 kg) for M, and (551852 s) for T. I get (1.89e^7 m) for the radius. Then I subtract 1,153,000 meters from my answer to account for the radius of Pluto. My final answer in meters is (1.77e^7 m). My final answer in km is (1.77e^4 km). However, when I input this, the system shows this is wrong. I've tried several variations of the answer, but nothing works. Does anyone know if I've overlooked something in the equation? Thanks.
  2. jcsd
  3. Feb 20, 2010 #2


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    Homework Helper

    Seems right.
  4. Feb 20, 2010 #3


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    Homework Helper

    I get the same answer.
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