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Homework Help: Potential Energy HW problem - Help

  1. Feb 15, 2010 #1

    woo

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    1. The problem statement, all variables and given/known data
    So this is my first post and, I've been working on this problem for a while and am having trouble wrapping my head around it... I tried searching but couldn't find anything that helped..
    So here's the problem.

    In one dimension, the magnitude of the gravitational force of attraction between a particle of mass M1, and one of mass M2 is given by:
    Fx(x)=GM1M2/x2
    Where G is a constant and x is the distance between the particles.

    a) What is the potential energy function U(x)? Assume that U(x) -> 0 as x -> infinity.
    b) How much work is required to increase the separation of the particles from x=x1 to x=x1+d?


    2. Relevant equations

    -dU(x)/dx=Fx(x)


    3. The attempt at a solution
    The solution given in the book is..a) U(x)=-Gm1m2/x
    b) Gm1m2d/x1(x1+d)

    Here is what I've been trying..
    -dU(x)/dx=Gx1x2/x2

    U(x)-U(x0)=-[tex]\int[/tex](Gm1m2/x2)dx
     
    Last edited: Feb 15, 2010
  2. jcsd
  3. Feb 15, 2010 #2
    Yep. Now simply do the integral. And apply your boundry condition U(inf) = 0
     
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