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Homework Help: A mass spring system

  1. Jun 3, 2007 #1
    1. The problem statement, all variables and given/known data

    http://img174.imageshack.us/img174/364/favt1ot7.jpg [Broken]

    2. Relevant equations

    a energy balance and a F=ma in z-direction

    3. The attempt at a solution
    I will neglect D (is that reasonable?) Use an energy and force balance:

    \frac{1}{2} k (\sqrt{(w/2)^2 + h^2} - L0 )^2 = mg\Delta H + D\Delta H,\ H=h+w/2.....eq1

    3.8mg= 2cos( \alpha)* k * ( \sqrt{ (w/2)^2 + (w/2)^2} - L{0} )


    with\ \alpha = arccos( (w/2) / ( \sqrt{ (w/2)^2 + (w/2)^2 }...... eq2

    2 eq's with 2 unknowns => L0 and k

    solve it leads to complex L0 and k! What am I doing wrong?
    Last edited by a moderator: May 2, 2017
  2. jcsd
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