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Question about transverse standing wave including violin string

  1. Jul 3, 2006 #1
    I have a question on this problem
    1. 10. A violin string vibrates at 335 Hz when unfingered. At what frequency will it vibrate if it is fingered one half of the way down from the end?

    For this one I worked out that string is fixed at both ends because its in a violin so I am thinking of using f=n v/2L where L=1 lambda/2 and v= lambda f. So overall it comes out to be f= nf, so in this case the n would be 1, right so the answer would be the same...right???
    I dont know if this is the right approach but this is what I am thinkin...any suggestions might help me figure out this problem..
    Thanks!!!
     
  2. jcsd
  3. Jul 4, 2006 #2

    Kurdt

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    The 'fingered' reference refers to actually holding the string down at its midway point making the string half the length of the unfingered or open position. It is not a reference to plucking half way down the string as I believe you have taken it to be.
     
  4. Jul 4, 2006 #3
    Yes, I agree with Kurdt .
    Also note that at the point of fingering , there exists a node .
    What is the value of n then ?
     
  5. Jul 4, 2006 #4
    so that means the value of n would be 1/2, right???? because it's fingered half way through the wave. Wouldn't n be a whole number..I really have no idea
     
  6. Jul 4, 2006 #5

    Kurdt

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    The string becomes fixed at a new position (i.e. L/2) so find the frequency of the string with this length instead of the old.
     
  7. Jul 4, 2006 #6
    so basically the new frequency is half of original one which would be 167.5 Hz, right??? because if I substitute this in place of L I get f= n f/2 which comes out to be 335/2= 167.5...right? Am I making sense?
     
  8. Jul 4, 2006 #7

    Kurdt

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    I think your algebra is a little out it should be double but I'll leave it to you to try and find your mistake. If you still have trouble don't hesitate to post again.
     
  9. Jul 4, 2006 #8
    Yes, it should be double.
    Can you physically "see" why the frequency increases ?
    As suggested you have made some algebraic error .
    _______________________________________________

    Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.
    Albert Einstein
     
  10. Jul 4, 2006 #9
    You guys are right...I made a stupid algebraic mistake and figured it out to be 670 Hz instead of 167.5 Hz. I plugged in L/2 in the wrong place...stupid substitution error...Thanks a lot for helping me, guys.
     
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