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Simple harmonic motion velocity and acceleration

  1. Apr 13, 2009 #1
    1. The problem statement, all variables and given/known data

    An oscillator consists of a block attached to a spring (k = 125 N/m). At some time t, the position (measured from the system's equilibrium location), velocity, and acceleration of the block are x = 0.800 m, v = -11.3 m/s, and a = -119 m/s2

    (a) calculate the frequency of oscillation (Hz)

    (b) calculate mass of block (kg)

    (c) calculate the amplitude of motion (m)

    2. Relevant equations
    v(t) = -angular frequency(displacement)sin(phase)
    a(t) = - angular frequency^2(displacement)cos(phase)
    phase = angular frequency(t) + phase angle

    3. The attempt at a solution

    -11.3 = -angular frequency (.8) sin (angular frequency x t + phase angle) but i have 3 variables

    i feel like there is some simple and fairly easy way to do this... i just dont know what it is

    thank you for the help

  2. jcsd
  3. Apr 13, 2009 #2


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    Homework Helper

    So isn't

    a(t) = - ω2*x(t)

    and since F = m*a = -k*x then substituting for a ...

    ω2 = k/m
  4. Apr 13, 2009 #3
    thank you very much that was quite helpful, but im having some problems with the amplitude calculation...

    i found the equation K = Ma/A where A is amplitude but that just gives me the original displacement

    125 = (.84 x -119)/ A

    A = .8

    any ideas?
  5. Apr 13, 2009 #4


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    Staff Emeritus
    Science Advisor
    Gold Member

    What will the acceleration and velocity be when the bob is at a maximum displacement?
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