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Homework Help: A satellite in orbit

  1. Dec 10, 2004 #1
    http://upload.cybermart.ca/2004/hepmesad.gif [Broken]

    I can't decide what to do with this question. I am studying for a final. I converted 24 hours to seconds and tried using the Fg = -gmm/r but I dont think thats going to work...

    any leads? Thanks guys
    Last edited by a moderator: May 1, 2017
  2. jcsd
  3. Dec 10, 2004 #2
    You're on the right track. Think about circular motion, too.
  4. Dec 10, 2004 #3
    ok I think im getting it.

    r*(omega)^2 = GM/r^2

    then i can cancel the R's to get

    Omega^2 = GM/r ?
  5. Dec 10, 2004 #4


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    Yes,it's correct.To check your answer,though,u should be gettin round about 35000km.
  6. Dec 11, 2004 #5
    you mean omega^2 = GM/r^3
  7. Dec 11, 2004 #6
    That's one of my favorite problems.

    I think the answer is about 24,000mi. Don't forget to subtract the radius of the earth. I always forget to do that!
  8. Dec 11, 2004 #7
    i Think radius should be (R+r) and use F=GMm/(R+r)^2
  9. Dec 11, 2004 #8


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    Why complicate?Use "r" as your length variable (the radius of the trajectory)and then,once u got the result,subtract the mean radius of the Earth which is round about 6371km.
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