1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    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

    User Avatar

    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook