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Homework Help: Finding mass of an object on a spring, given Frequency

  1. Apr 12, 2016 #1
    1. The problem statement, all variables and given/known data
    A mass m at the end of a spring oscillates with a frequency of 0.84 Hz . When an additional 730 g mass is added to m, the frequency is 0.65 Hz .

    2. Relevant equations
    f*2pi = w
    w = (k/m)^1/2
    f = (1/2pi)*(k/m)^1/2

    3. The attempt at a solution
    I simply used the third equation twice, rearranging to the following:
    m = k/(2pi*f)^2
    using this equation two different times I ended up with:
    m = k / (2pi*.84)^2
    m + .73 = k / (2pi*.65)^2
    I solved the above equations for m and came out with the wrong answer.

    Any help is greatly appreciated! Thanks in advance : )
  2. jcsd
  3. Apr 12, 2016 #2


    User Avatar

    Staff: Mentor

    Can you show your math at the end where you solve the two equations for m? That may help us spot any errors... :smile:
  4. Apr 12, 2016 #3
    Haha, so I attempted to solve my systems of equations three different times and got a very large negative mass, I just attempted it again and got the correct answer.
    Sorry about that ... cheers
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