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    Planet A and planet B are in circular orbits around a distant star. Planet A is 5.5 times farther from the star than is planet B.

    What is the ratio of their speeds Va/Vb?

    So I know that (rA/rB)^3 is equal to (Ta/Tb)^2 and I can find the ratio of their periods (basically, (5.5/1)^1.5). How do I go from here?

    On another note, is this question actually Keplerish? Should I just be assuming that they both take the same time to finish one orbit and do circular geometry?
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    omega = 2*pi/T
    v = omega*r
    So you should be able to get v ratios.

    They don't take the same time to finish an orbit, if they did, ratio of T would be 1 which it isn't.
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    mv^2/r = GMm/r^2

    so

    v^2 = GM/r

    so

    v1^2/v2^2 = r1/r2
 
 
 

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