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Homework Help: Gravitation course work

  1. Apr 18, 2008 #1
    1. The problem statement, all variables and given/known data

    A planet around a star has an orbit that is not exactly an ellipse. In addition to the dominant Fo [tex]\alpha[/tex] r^-2 term due to gravity from the central star, the planet seems to be responding to a slight additional force which has the form F1 [tex]\alpha[/tex] r^-[tex]\alpha[/tex] where [tex]\alpha[/tex] is some constant.

    2. Relevant equations

    Included in 1.

    3. The attempt at a solution

    Where do I begin?
  2. jcsd
  3. Apr 18, 2008 #2


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    I have no idea since I don't know what you're supposed to be doing.
  4. Apr 18, 2008 #3
    Sorry, part of this seems to have been cut off.

    Assuming there is a slight background density of material with spherically symmetric density p1 falling off as p1 (alpha) r^-B

    Find the value of B in terms of alpha
  5. Apr 18, 2008 #4
    Can anyone help me get started please? I don't understand this at all and it's due soon.
  6. Apr 18, 2008 #5


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    Near as I can tell you want to assume there is a mass distribution with density rho(r)=p1*(r/r0)^(-B). Now you want to figure out the radial dependence of the force it generates. Compute total mass as a function of r, M(r). Use that to calculate the force.
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