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Homework Help: Two springs supporting a mass verticle

  1. May 30, 2014 #1
    1. The problem statement, all variables and given/known data
    Two springs have spring constants k1 and k2, are in a vertical position to support a single object of mass m. Show that the angular frequency of oscillation is ((k1+k2)/m)^(1/2) if the springs are in parallel.

    3. The attempt at a solution

    The book then goes on to explain
    F = ma = -k1*x - k2*x
    a + ((k1+k2)*x) / m = 0
    where (k1+k2)/m = w^2
    my question is why is gravity neglected?
  2. jcsd
  3. May 30, 2014 #2

    Doc Al

    User Avatar

    Staff: Mentor

    They aren't really neglecting gravity. Note that the displacement (the x) is measured from the equilibrium position, so the effect of gravity is already included. (Gravity, being a constant force, merely shifts the zero point.)
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