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Homework Help: Will someone check my application of kepler's laws?

  1. Sep 28, 2008 #1
    1. The period of the Earth's orbit is approximately 365.25 days. Use this fact and Kepler's Third Law to find the length of the major (not semi-major) axis of the Earth's orbit. You will need the mass of the sun, M = 1.99x10^30 kg, and the gravitational constant, G = 6.67x10^-11 Nm^2/kg^2.

    2. It's possible to place a satellite into orbit about the Earth so that it remains fixed above a given location on the equator. Compute the altitude that is needed for such a satellite. The Earth's mass is 5.98x10^24 kg; its radius is 6.37x10^6 m.

    Sorry, I couldn't figure out how to get the equations from microsoft equation editor into the question, so you'll have to open the attachment (you may have to save it, I apologize). I've got full solutions worked out, so all I need is for someone to double check me.
    Thanks in advance!

    Attached Files:

    • math.doc
      File size:
      35.5 KB
    Last edited: Sep 28, 2008
  2. jcsd
  3. Sep 28, 2008 #2


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    Staff Emeritus
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    First one you have the wrong answer. You forgot to convert days to seconds. Also your maths in the various stages is a little off. I'll let you see if you can spot what it is.

    Second one is slightly off as well. I think thats just arithmetic.
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