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Homework Help: Tension in guitar string

  1. Jan 2, 2010 #1
    A guitar string 60 cm in length, with a diameter of 1.4 mm and a tension of 289 N, emits a note with a frequence of 147 Hz. Find the frequency in each of the followig situations:

    a)the tension isreduced to 196N
    b)a string of the same material, 45 cm long and 1mm in diameter under 168 N of tension, is plucked.

    I have no idea for a, but I was hoping someone could check my work on b?
    =Fi(square root of tension fraction)(length fraction)(diameter fraction)
    =147Hz(square root of 169/289)(60/45)(1.4/1)

    I am just getting confused as to if the 289 goes on top of the fraction, or the 169.

    thanks for your help in advance!
  2. jcsd
  3. Jan 2, 2010 #2


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    It would help if you put units in the equations then you can easily check that you have them the correct way around.

    frequency = sqrt ( Tension / mass per unit length )
    s-1 = sqrt ( N / Kg m -1 )
    s-1 = sqrt ( kg m s-2 / Kg m -1 ) = sqrt(s-2)
  4. Jan 2, 2010 #3
    thankyou. Can you please help me with part a as well?
  5. Jan 2, 2010 #4


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    The frequency is proprtional to sqrt(tension)
  6. Jan 2, 2010 #5
    thanks again
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