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Homework Help: Annoying ellitpical orbit problem

  1. Mar 10, 2010 #1
    1. The problem statement, all variables and given/known data

    a planet in elliptical orbit about a star has speed of 100 m/s at its closest approach of 1X 10^10m . what is the speed at its furthest approach of 3X10^10m? What has happened to its total mechanical energy?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Mar 10, 2010 #2


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    Homework Helper

    You have to at least give it a try before asking for help.
  4. Mar 10, 2010 #3
    I tried to figure out it using mGh+1/2mv^2 = mechanical energy original = mechanical energy final. However, I know there has to be an easier way to do it, using ratios. Could you please tell me the trick?
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