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Homework Help: Orbits and Potential Energy

  1. Jul 11, 2005 #1

    I really don't even understand what this problem is talking about! If someone could just point me in the right direction, I would appreciate it!

    A satellite is placed in a noncircular orbit about the Earth. The farthest point of its orbit (apogee ) is 4 Earth radii from the center of the Earth, while its nearest point (perigee ) is 2 Earth radii from the Earth's center. If we define the gravitational potential energy U to be zero for an infinite separation of Earth and satellite, find the ratio U perigee/U apogee .

  2. jcsd
  3. Jul 11, 2005 #2


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    Science Advisor
    Homework Helper

    The first sentence doesn't sound good. I mean are any words or concepts unclear in the problem's text...?

  4. Jul 11, 2005 #3

    Doc Al

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    Staff: Mentor

    Start by looking up (or, better yet, deriving) the general expression for gravitational potential energy, which comes from Newton's law of gravity. Hint: U depends on the masses and the distance from the center of the earth.
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