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Homework Help: Simple Harmonic Motion: Calculate Max Velocity

  1. Apr 19, 2014 #1
    1. The problem statement, all variables and given/known data
    A mass of 0.4 kg, hanging from a spring (k= 80N/m) is set into an up-and-down SHM. What is the speed of the mass when moving through the equilibrium point? The starting displacement, A, is 0.10 m.

    2. Relevant equations
    a = -kx/m
    ω = 2pi/T

    3. The attempt at a solution
    I tried to apply one of the equations of motion: 2ax = vf^2 - vi^2: but I got an answer of 2 m/s, which is incorrect as the correct answer is 1.4 m/s. Now, I realize that acceleration is not uniform which means that I can't use that equation.
    However, I'm not sure what else to do. Using a = -kx/m I managed to calculate the acceleration at the equilibrium point, but without any sort of time or time period or frequency, I haven't a clue how to solve this question.
    Last edited: Apr 19, 2014
  2. jcsd
  3. Apr 19, 2014 #2
    Use energy conservation.
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