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Homework Help: Elliptical orbit question

  1. Mar 21, 2010 #1
    1. The problem statement, all variables and given/known data
    a satellite is set to orbit a planet of mass 4X 10^20 kg .
    It is placed at a distance of seperation of 10^7m with a velocity of 30 degrees to the line connecting the center of the planet and the satellite. What will be its eccentrity fo orbit? (Answer is .89)

    2. Relevant equations
    ME = KE + PE
    KE = 1/2 mv^2
    PE = -GMm/r

    3. The attempt at a solution
    I did 40m/s *sin (30) = vertical velocity.
    Then, I plugged it into the equation -GMm/r = .5m(40m/s *sin (30))^2 + -GMm/r

    I didn't get the answer though...
    please help!
  2. jcsd
  3. Mar 22, 2010 #2
    help plz
  4. Mar 22, 2010 #3

    Filip Larsen

    User Avatar
    Gold Member

    You may want to think (or read in your textbook) about how eccentricity (e) is related to the semi-major axis (a) and semi-latus rectum (p), and how those two again are related to the information you were given in the problem text.
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