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Homework Help: Mass on Spring

  1. May 25, 2010 #1


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    1. The problem statement, all variables and given/known data

    Two identical masses m1 = m2 = m are connected by a massless spring with
    spring constant k. Mass m1 is attached to a support by another massless spring with
    spring constant 2k. The masses and springs lie along the horizontal x-axis on a smooth
    surface. The masses and the support are allowed to move along the x-axis only. The
    displacement of the support in the x-direction at time t is given by f (t) and is externally
    controlled. Write down a system of diļ¬€erential equations describing the evolution of the
    displacements x1 and x2 of the masses from their equilibrium positions.

    2. Relevant equations

    3. The attempt at a solution

    Is it: mx1'' = -k[x1-f(t)] + k[x2-x1-f(t)]

    mx2" = -k[x2-x1-f(t)]


  2. jcsd
  3. May 25, 2010 #2


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    Homework Helper

    Check your equations. The force exerted by a spring depends on the change of its length. Does an other spring effect this force?
    Read the problem, are the spring constants equal?

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