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Homework Help: Finding amplitude? SHM problem

  1. Dec 12, 2009 #1
    Finding amplitude??? SHM problem

    1. The problem statement, all variables and given/known data
    A 245 g mass attached to a horizontal spring oscillates at a frequency of 3.70 Hz. At t =0s, the mass is at x= 4.40 cm and has v_x = -25.0 cm/s.

    2. Relevant equations
    I got the first two
    The Period= .27027 s
    The Angular Frequency= 23.248 rad/s
    The Amplitude=? m rounded to 5 sig figs
    The Phase Constant=? rad rounded to 5 sig figs

    3. The attempt at a solution

    I tried using the equation (x)t=Acos([tex]\omega[/tex]t+[tex]\phi[/tex])
    and plugged in t=0 and .0440m for x(0) so the answer i got was .0440m but this is wrong. and i can't attempt the phase constant yet because i need the Amplitude for that. Any help is appreciated thanks.
  2. jcsd
  3. Dec 12, 2009 #2


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    Homework Helper

    Re: Finding amplitude??? SHM problem

    Yes you can. You're off to the right start, but you'll need another equation to determine the phase constant. Hint: there's another value you're given in the problem that you haven't used. What can you do with it?
  4. Dec 14, 2009 #3
    Re: Finding amplitude??? SHM problem

    I'm guessing that the velocity has something to do with it and maybe the other equation for velocity v(t)= -A[tex]\omega[/tex]sin([tex]\omega[/tex]t+[tex]\phi[/tex])??
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