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Homework Help: Bulk Modulus of unknown material

  1. Dec 12, 2012 #1
    1. The problem statement, all variables and given/known data
    A extremely strong wire of exotic material has a radius of 0.1 mm and a length of 5 m. A 1000 kg
    mass is hung vertically from the wire. The speed of sound in the wire is observed to be the same as
    the speed of a transverse wave on the wire. What is the Bulk Modulus of the material? (in N/m2

    2. Relevant equations
    Speed of Sound in solid: v=√(B/ρ)

    3. The attempt at a solution
    I honestly don't know where to start. All the examples in my text give a change in volume or pressure, which would be simply using Equation 2. I'm assuming you find the density of the wire somehow, but I don't have the mass of the wire. Any guidance would help!
  2. jcsd
  3. Dec 12, 2012 #2


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    Staff: Mentor

    You have the tension in the string (assuming this experiment was done on earth), this is related to speed of transversal waves via the (line) density of the material.
  4. Dec 12, 2012 #3
    OHHH. I SEE. I get it now! Thank you!!
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