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Homework Help: Find the orbital period

  1. Nov 30, 2013 #1
    1. The problem statement, all variables and given/known data If a satellite is to orbit Earth at an altitude of 1.00x10^3 Km, what would be its orbital period? rs = 1.00x10^3 km, Mearth = 5.97x10^24 kg, Gravitational Constant = 6.67x10^-11

    2. Relevant equations

    T= 2∏√r^3/GM

    3. The attempt at a solution rs = 0.815484549m (i converted the satellite's altitude to meters) T= 2∏√0.815484549^3/6.67x10^-11 x 5.97x10^24 = error in my calculator ):

    Edit: i did not convert km into meters correctly so it would be 1 meter

    2∏√1^3/6.67x10^-11 x 5.97x10^24
    Last edited: Nov 30, 2013
  2. jcsd
  3. Nov 30, 2013 #2


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    Staff: Mentor

    Where does "0.815484549" come from? Also, keep in mind that altitude is not the same thing as radius :wink:
  4. Nov 30, 2013 #3
    In my class i have to convert Km to meters so i divide it by 100. So to find the radius of the satellite do i have to add the radius of the earth to the altitude of the satellite?


    EDIT: I mean 1000 so it would be 1m oops
  5. Nov 30, 2013 #4

    D H

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    Staff Emeritus
    Science Advisor

    Think! 1 kilometer is 1000 meters, not 0.01 meters. Aside: How did you get 0.815484549 meters by dividing 1.00x10^3 km by 100? (And once again, you do not want to divide by 100.)

    Altitude means height above the surface of the Earth, so to get the distance from the center of the Earth you need to add the Earth's radius to the altitude.
  6. Nov 30, 2013 #5


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    Staff: Mentor

    Each km is 1000 meters. So to convert km to meters, multiply by 1000. Thus, 1000 km is 1000 x 1000 meters. And yes, add the Earth radius to the altitude to determine the orbital radius.
  7. Nov 30, 2013 #6
    when i divided km by 100 i was thinking cm into meters (because 100cm = 1m ) and yes i got 0.815484549m by doing 1.00x10^3 km by 100, it was pretty stupid of me and thanks for your help
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