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Homework Help: Kepler's Laws problem

  1. Apr 26, 2012 #1
    1. The problem statement, all variables and given/known data
    Comet Halley approaches the Sun to within 0.570 AU, and its orbital period is 75.6 yr. (AU is the symbol for astronomical unit, where 1 AU = 1.50 x 1011 m is the mean Earth-Sun distance.) How far from the Sun will Halley's comet travel before it starts its return journey.

    2. Relevant equations
    Can anyone help me with this?

    3. The attempt at a solution
    I've already figured that .57 AU = 8550 m
  2. jcsd
  3. Apr 26, 2012 #2


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    Staff: Mentor

    Your value for rp, the perihelion distance, looks a tad small. Did you lose a few orders of magnitude somewhere? :smile:

    If you choose an appropriate unit system you shouldn't have to do any conversions :wink:

    Which of Kepler's laws do you think might be applicable here, given the values that you know.
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