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Homework Help: Newton's Law of gravitation using kepler's laws.

  1. Sep 23, 2007 #1
    1. The problem statement, all variables and given/known data

    Derive Newton's Law of gravitation using kepler's laws.

    2. Relevant equations

    Kepler's law equations.

    3. The attempt at a solution

    l= r(1- e*cos(theta)) l- const. e- eccentricity
    Solving these equations using kepler's laws (r^2(d(theta)/dt), etc.)

    second time derivative of r = -4c^2/(lr^2) + 4c^2/r^3
    subtracting centrifugal acc. (4c^2/r^3) from it I get Newton's law.

    But I don't know how the centrifugal acc. come here.
  2. jcsd
  3. Sep 23, 2007 #2
    someone reply. :(
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