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Homework Help: Curious about Linear Density (μ) of a string

  1. Dec 4, 2008 #1
    (Sorry I cannot follow the question format because this question is related to a problem, but is not the problem itself.)

    I am talking about the linear density μ that appears in this equation:
    v = sqrt(T/μ)

    .. used usually for musical instruments, where μ = m/L

    Now, I am wondering which value of L we use.

    Say that you have a string that is normally .1 kg and .10 meters long.
    Now lets say that u stretch the string to .12 meters to make some musical instrument.

    For L value, do we plug in .12 meters or .10 meters?

  2. jcsd
  3. Dec 4, 2008 #2


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    Homework Helper

    Usually in the musical instruments that mush stretching is not allowed. mu is the linear density of the wire. For a given length of wire ( which is usual in all the string instruments) linear density depends on the diameter and the material of the wire.
  4. Dec 5, 2008 #3
    But I specifically came across a question that required me to make a choice between using an unstretched length vs. a stretched length and I wasn't sure what to do.

    Let's hypothetically assume that someone stretched a .1 m wire to .12 m to create some musical instrument.
    Which value of L would u use?
  5. Dec 5, 2008 #4


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    Homework Helper

    Obviously 0.12 m.
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