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Homework Help: Need some help with differential equations for mechanics.

  1. Jan 30, 2013 #1
    1. The problem statement, all variables and given/known data

    I'm having problems with some differential equations, just need to know where I'm going wrong.

    2. Relevant equations

    3. The attempt at a solution

    a) mv[itex]\stackrel{dv}{dx}[/itex]=F(x)

    Setting F(x)=-kx

    I then have to find the position as a function of time..

    I'm not sure how to do that integral, though, or if that's even right.

    b) This problem involves a disc moving along a rough surface, so it has friction (F) and linear air resistance (-bv) acting on it.


    Thanks for any help!
  2. jcsd
  3. Jan 30, 2013 #2
    For a), transform the integrand to this form: ## \displaystyle \frac {a} {\sqrt {1 - (cx)^2 } } ##, then use the substitution ## u = cx ##.

    For b), you are not doing it correctly. You should have gotten ## \displaystyle \int \frac {dv} {F - bv}##.
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