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Homework Help: Kepler and the Comet

  1. Apr 15, 2008 #1
    1. The problem statement, all variables and given/known data

    A comet is 10 times farther from the sun than the Earth. Find the time it take to make its orbit around the sun.

    2. Relevant equations
    T^2/R^3 = K
    K= 3.36X10^18

    3. The attempt at a solution

    I tried to create a ratio, but I honestly have no idea where to start. I'm not even sure I need to know kepler's constant for this problem. and the answer is T=31.6

    I don't know what to put as R, and that leaves me with two variables, R and T.
    I also don't know if Kepler's constant is the same for the comet and the earth.
  2. jcsd
  3. Apr 15, 2008 #2
    since k is equal for both objects, you can set each objects time^2/distance^3 ratio equal to eachother. Then use that [tex]R_{comet}=10R_{earth}[/tex].
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