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Homework Help: Question on forces and ratios

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

    Here's the question:
    Two forces, Fa and Fb, are applied to an object. The larger force is Fa. When both forces point due east, the object's acceleration has a magnitude of 0.50 m/s^2. However, when Fa points due east, and Fb points due west, the acceleration has a magnitude of 0.40 m/s^2. Find the ratio of Fa/Fb of the magnitudes of the forces.

    2. Relevant equations

    F = ma ?
    d = Vt + 1/2at^2 ?

    3. The attempt at a solution

    I've tried manipulating the F = ma equation to no avail. Maybe it has something to do with d = Vt + 1/2at^2 but I think maybe I'd have to use Fa + Fb = sigmaF.
    But to be honest, I have no idea where to start, especially with finding ratios. I just need a little help forward. Thanks :smile:
     
  2. jcsd
  3. Sep 18, 2008 #2

    rl.bhat

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    Homework Helper

    Fa + Fb = ma1........(1)
    Fa - Fb = ma2.........(2)
    take the ratio of 1 and 2 and solve for Fa and Fb
     
  4. Sep 19, 2008 #3
    I've tried something like that, but the book says that the answer is 9. Does that change anything?
     
  5. Sep 19, 2008 #4
    Nevermind my last post, I've gotten the answer to be 9. Thanks! I'll know how to do ratios now :approve:
     
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