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Homework Help: Mass in oscillating spring

  1. Oct 2, 2008 #1
    1. The problem statement, all variables and given/known data

    The position of a mass oscillating on a spring is given by x(t) = (18.3cm)cos[(2.35s^-1)t] .
    What is the frequency of this motion?

    2. Relevant equations

    X= Amplitude x Cos (2pi/T x time)

    3. The attempt at a solution

    I know that frequency= 1/Period, im trying to use f= 1/(2.35s^-1) but it doesnt seem correct. Also i've tried multiplying the amplitude by 2.... f= 1/(18.3cm)x2


    Thanks
     
  2. jcsd
  3. Oct 2, 2008 #2
    so the form is [tex] x(t) = Acos( \omega t )[/tex]

    where [tex] \omega = 2 \pi f [/tex]

    Can you see how this helps you?
     
  4. Oct 2, 2008 #3
    so omega= 2.35s^-1

    and so to find frequency I could just do f=2.35s^-1/2pi

    I'm not sure about the reversing 1/1/T = s^-1
     
  5. Oct 2, 2008 #4
    Sorry I don't understand what you're saying here, but yes:

    [tex] f = \frac{\omega}{2\pi} [/tex]

    are you confused because omega is a reciprocal? That should play no part in exchanging frequency with period. So just follow that formula and you should be fine.

    Note: I have not solved the problem numerically, but I can tell it's going to be a very small answer.
     
  6. Oct 2, 2008 #5
    Thank you very much!
     
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