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Homework Help: Gravity Wells. Help me with the radius!

  1. Jan 6, 2013 #1
    1. The problem statement, all variables and given/known data

    I need to what the escape speed from the sun to mercury would be if the spaceship is 25 mil km away from the sun.
    2. Relevant equations

    3. The attempt at a solution
    Basically, all need to know is if I can do this:
    Gm1m2/radius of sun+ 25 mil km away from sun=1/2 mv^2.

    Also, as you get farther away you can decrease your speed. Correct?
  2. jcsd
  3. Jan 7, 2013 #2
    What is "escape speed from the Sun to Mercury"? The escape speed is usually defined from some location near a gravitating body to infinity, not to another body.
  4. Jan 7, 2013 #3
    Oh sorry, I meant just from the sun.
  5. Jan 7, 2013 #4
    Then your equation is correct.
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