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Homework Help: Standing waves and banjo string

  1. Oct 19, 2011 #1
    1. A banjo string 36.0 cm long oscillates in a standing wave pattern. It resonates in its
    fundamental mode at a frequency of 250 Hz. What is the tension in the string if 80.0 cm of the
    string has a mass of 0.75 grams?

    2. Relevant equations


    3. The attempt at a solution
    solved for miu and plugged into equation: 7.5*10^-4/.8
    --> v=2Lf
    then equated both equations

    i think i got confused with which length to use
  2. jcsd
  3. Oct 19, 2011 #2
    I think your work is ok.

    Yes - mu =m/L and for fundamental frequency lambda = 2L.
  4. Oct 19, 2011 #3
    I'm not sure when to use the length of the banjo string (36cm) :[
  5. Oct 19, 2011 #4
    When the string is vibrating in its first overtone, i.e. its second harmonic, then the length of string will be the wavelenght.
  6. Oct 19, 2011 #5
    thank u. my answer is still incorrect.... i would appreciate any more help. thank you
  7. Oct 19, 2011 #6
    May I correct my own contribution above.

    mu = m/L where L = 0.80m but lambda = 2 x 0.36 since this is the length which is oscillating.
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