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Homework Help: HELP w/ harmonics formulas

  1. Feb 9, 2008 #1
    I have been torturing myself with this problem for a couple weeks now and I am stumped. The unit I am working on is called simple harmonics. The question is:
    Prove that the maximum speed (Vmax) of a mass on a spring is given by 2(pi)fA
    I am guessing that the question wants me to re-arrange one of the formulas that was learned in this chapter but i am just lost.

    Here are the formulas related to this unit.
    Fx = -kx , W=1/2kx^2, T=[2(pi)r] / v , Et = 1/2mv^2 + 1/2kx^2, f = 1/2(pi) sq_rt(k/m)
    or f = 1/2(pi) sq_rt a/-x

    Please any help would be greatly appreciated
  2. jcsd
  3. Feb 9, 2008 #2


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    OK. First off are you in a calculus based course? I ask because this can be proved in one to two lines with calculus.
  4. Feb 10, 2008 #3
    somewhat. we learned trigonomic method. cosine law and pathagorean theorem
  5. Feb 17, 2008 #4
    anyone ??
  6. Feb 17, 2008 #5


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    Do you know how to take a derivative?

    If not, then try starting the problem this way:

    Start with your energy equation:

    Et = 1/2mv^2 + 1/2kx^2

    First, try to get Et in terms of the wave's amplitude.

    After this, fill in all the information for when v=v_max. Can you take it from here? If not, show me how far you can get.
    Last edited: Feb 17, 2008
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