i was hoping somebody could give me a hand with a homework problem i have .(adsbygoogle = window.adsbygoogle || []).push({});

first here's the question .

-> Planet X has two satellites . A and B . Both orbits are circular . Satellite A's orbital radius is 4 times B's orbital radius . calculate the following ratios .

a) A's orbital period / B's orbital period

b) A's orbital speed / B's orbital speed

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now i'm kind of stumped because of the lack of information .

for a) i know that the ratio of orbital periods is the ratio of the T's . but i'm absolutly losing it trying to figure out how to find the T's .

i know that ((4pi^2)/G) (R^3/T^2) ) = M1 + M2

and R^3 = T^2 , also C = 2piR . but i can't for the life of me see how i could get the desired ratio with those formulas . does anybody know if i'm on the right track ? or should i be using some other formula that i'm somehoe missing ?

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# Homework Help: Circular orbits

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