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Homework Help: Single Degree-of-Freedom Systems

  1. Feb 28, 2014 #1
    An SDOF system (m = 20 kg, k = 350 N/m) is given an initial displacement of
    10 mm and initial velocity of 100 mm/s. (a) Find the natural frequency; (b) the
    period of vibration; (c) the amplitude of vibration; and (d) the time at which the
    third maximum peak occurs.
    Ans: 0.666 Hz; 1.502 sec; 25.91 mm; 3.285 sec.

    Which Equation should I use to obtain the amplitude of vibration and time for the third maximum pick occur?

    Part a and b I got the answer.
  2. jcsd
  3. Feb 28, 2014 #2


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    Science Advisor
    Gold Member

    That's a harmonic oscillator, isn't it? Calculate the total energy (kinetic plus potential) at the initial moment from the equation ##E=\frac{1}{2}mv^{2}+\frac{1}{2}kx^{2}##, and find out what displacement ##x## it corresponds to if all the energy were potential energy. That way you can find the amplitude of oscillation.
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