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Predicting Equilibrium?

  1. Oct 26, 2004 #1
    I have this homework question that I an having a lot of trouble with. I am not sure if anyone could help, but here it is:

    Using the definitions of torque and lever arm and the fact that the system is in equilibrium, derive this formula-
    Xo= m1x1 + m2x2 + m3x3
    ....... m1 + m2+ m3

    So, I know all the different formulas for torque and the levers etc... but I can't figure out how to turn them into this formula?
     
  2. jcsd
  3. Oct 26, 2004 #2

    Galileo

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    Mind telling what [itex]x_0,x_1,x_2,x_3[/itex] are?
    All I can tell is that the equation can be written as such:
    [tex]m_1(x_1-x_0)+m_2(x_2-x_0)+m_3(x_3-x_0)=0[/tex]

    Maybe that helps...
     
  4. Oct 27, 2004 #3
    That does help, here are some of the given equations in the chapter before the problem:

    T1=m1gl1 T2=m2gl2 l1=Xo-X1 l2=Xo-X2 l3=Xo-X3

    The numbers in the equation:
    Xo= 121.8(.3000) + 71.40(6500) + 145.4(.5005)/ 121.8 + 71.40 + 145.4


    121.8=m1(hanging mass from bar on the left) 71.40=m2(hanging mass on the right)
    145.4=m3(mass from the center of gravity) and we are looking for Xo-the balance point in between m1X1 and m3X3 wih m2X2 on the right of m3X3

    Does that help or make it more confusing?
     
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