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Homework Help: Oscillating spring problem

  1. Jan 30, 2016 #1
    1. The problem statement, all variables and given/known data
    A 3kg object is attached to a spring and oscillates with an amplitude of 10 cm and frequency f = 2 Hz

    a.) What is the force constant k of the spring?
    b.) what is the total energy of this motion?
    c.) Write an equation for x(t) describing the position of this object relative to its equilibrium position. Can phase constant be determined from the information given?

    2. Relevant equations
    k = (4π^2)(m)/T^2
    TE= 1/2kx^2+1/2mv^2
    1/2kA^2 = 1/2kx^2+1/2mv^2

    3. The attempt at a solution

    a.) k = 4π^2(3)/(0.5)^2 = 473.74
    b.) First I attempted to find the velocity from the equation 1/2kA^2 = 1/2kx^2+1/2mv^2 I have trouble putting something in for x. Should I just put the amplitude in for x?
    c.) x(t) = 0.01sin(4π t + φ)
  2. jcsd
  3. Jan 30, 2016 #2


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    Welcome to PF!

    Parts (a) and (c) look good except that you have not included units. Do you need to worry about significant figures?

    Hint for (b): Does it matter at which point of the motion you calculate the energy?
  4. Jan 31, 2016 #3
    Thank you!
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