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Homework Help: Mass of sculpture given fm, mass, lengths etc

  1. Jan 19, 2014 #1
    1. The problem statement, all variables and given/known data

    A heavy sculpture is suspended by a steel wire that is 91.0 cm long and has a mass of 5.40 g. In a strong wind, the wire hums at its fundamental frequency of 97 Hz. What is the mass of the sculpture?

    2. Relevant equations

    v = sqrt(T/μ)

    μ = m/L

    3. The attempt at a solution

    I am pretty lost here. There is no velocity involved in the equation (I think) so I can't use the first equation, I tried messing around with the second equation and then plugging fm into v but no luck. Is there maybe an equation that I am missing here? Help!
  2. jcsd
  3. Jan 19, 2014 #2


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    Homework Helper

    You have not included the "experimental" equation, v = lambda f.
    The "strong wind" is putting vibrational Energy into the wire, it is not blowing the sculpture sideways, which would increase the wire Tension.
    So, the Tension is only caused by the sculpture weight mg.
    the Wave excited by the string is resonating at the fundamental;
    this means that the 2nd reflection reinforces the original wave; the wire displacement (transverse to its length) looks like ½ of a sine wave (node on both ends).
    Once you recognize the wavelength, you can determine the wave velocity - then the Tension.
  4. Jan 19, 2014 #3


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    Gold Member

    tg22542, it can lead you well astray if you remember equations but not what the variables in them stand for. What did you think v stood for in v = sqrt(T/μ)?
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