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Calculate number of nodes in stationary waves

  1. Jul 10, 2013 #1
    1. The problem statement, all variables and given/known data

    Hi guys I have this problem that I can't solve..

    Suppose to have this situation:

    12345.jpg

    when M=16kg the cord vibrates in one of its normal ways of oscillation.
    when M=6.25 we have the same frequency but 3 more nodes.

    How many are the nodes of the stationary wave in the first and in the second case?


    Knowing that for the n harmonic the frequency is

    [itex]\frac{n}{2L}\sqrt{\frac{T}{u}}[/itex]

    3more node → n harmonic first case +2 so

    [itex]\frac{n1}{2L}\sqrt{\frac{T1}{u}}[/itex]=[itex]\frac{n2}{2L}\sqrt{\frac{T2}{u}}[/itex]

    but it's wrong.

    How can I solve this?

    Thanks in advance.
     
    Last edited: Jul 10, 2013
  2. jcsd
  3. Jul 10, 2013 #2
    I think i would be n+3 not n+2 for three more nodes
     
  4. Jul 10, 2013 #3
    yes I think you're right

    edit.

    solved
     
    Last edited: Jul 10, 2013
  5. Jul 10, 2013 #4
    I worked the problem and I am curious what the answer is?
     
  6. Jul 11, 2013 #5
    Last edited: Jul 11, 2013
  7. Jul 11, 2013 #6
    Let me ask for a definition. If the string is vibrating at its lowest frequency, do you consider the endpoints f the string where it attaches to the wall and pully nodes or do the nodes only exist BETWEEN the end points? Put another way does the fundamental frequency have 0 or 2 nodes?
     
  8. Jul 11, 2013 #7
    I consider the fundamental have 2 nodes like this schema

    250px-Harmonic_partials_on_strings.svg.png
     
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