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Minimum height for a satellite to remain over the same geographical point

  1. Feb 12, 2005 #1
    a.)calculate at what height above the earth's surface a satellite must be placed if it is to remain over the same gerographical point on the equator of the earth. b.)what is the velocity of such a satellite?

    i have no idea how to do the question, but i know it has to do with these equations:
    Fcent.=Fgrav.
    m(v^2)/r=GMm/(r^2)

    because my book doesn't have answers for this question, i don't know the answer for this question.

     
  2. jcsd
  3. Feb 12, 2005 #2

    dextercioby

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    That's the equation u need to use,but under an equivalent form.Now find "r" by plugging the correct numerical values...

    Daniel.

    P.S.HINT:relate angular velocity to tangent velocity...
     
  4. Feb 12, 2005 #3
    dextercioby, can you please show me some work or maybe even tell me the answer. i am stuck becuase i found that there are two variables, "v" and "r", are unknown.
     
  5. Feb 12, 2005 #4

    dextercioby

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    Yes.[itex] v=\omega r [/itex].And now u have only one variable,namely 'r'...

    Daniel.
     
  6. Feb 12, 2005 #5
    sorry for my ignorance, but what is the w(or omega) thing stands for?
     
  7. Feb 12, 2005 #6

    dextercioby

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    Angular velocity of the Earth's rotation motion.U can find it knowing the period of rotation ("length" of a mean day) and the value of [itex] \pi [/itex],which can be approximated to [itex] 3.14 [/itex]

    Daniel.
     
  8. Feb 12, 2005 #7
    i found the answer for part a of my question to be 35870 km, can you please approve it. thanks alot so far.
     
  9. Feb 12, 2005 #8

    dextercioby

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    It seems correct.However,for point b) u'll need another number,or u can use this 35870Km,but indirectly.

    Daniel.
     
  10. Feb 12, 2005 #9
    anyways (i have a feeling that you arn't going to do the question for me), thanks very much dextercioby for your quick response, it helps me a great deal.
     
  11. Feb 12, 2005 #10
    lol....k thanks
     
  12. Feb 12, 2005 #11

    dextercioby

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    Tell me what number you get for velocity...

    Daniel.
     
  13. Feb 12, 2005 #12
    does 3072.6 m/s sounds good?
     
  14. Feb 12, 2005 #13

    dextercioby

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    Pretty much so.

    Daniel.
     
  15. Feb 12, 2005 #14
    k, thanks again. :smile:
     
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