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Phyiscs- Beats and frequency problem

  1. Apr 29, 2013 #1
    1. The problem statement, all variables and given/known data

    2. Relevant equations
    fb=f2-f1 or f1-f2

    3. The attempt at a solution
    Well, i know how to calculate the beat difference, but I do not under stand which of the 303Hz or the 297Hz referred to question #4 are the correct initial frequencies before adding the Plasticine!!! Can some one explain that to me please!

    Thank you for your time.
  2. jcsd
  3. Apr 29, 2013 #2


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    I don't think I understand the question. Could you include the problem statement for #4?
  4. Apr 29, 2013 #3


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    Staff: Mentor

    Hi sakonpure6. You're providing the answer, so I'll try to figure out the question ... [Broken]

    It sounds as though you have 2 tuning forks with a certain beat frequency. You then add plasticine to one of the tines, the effect being to lower the resonant frequency of that fork. If in doing so the beat frequency reduces to 1Hz, what was that fork's resonant frequency without the plasticine?

    I think you still need some detail from the question #4 that you allude to, though I'm left to guess.
    Last edited by a moderator: May 6, 2017
  5. Apr 30, 2013 #4
    Since I cant see the edit button, here is question 4 and I really appreciate this guys!!!

    Two tuning forks are sounded together, producing three beats per second. if the first fork has a frequency of 300 Hz , what are the possible frequencies for the other fork?

    The answers are: 297Hz and 303Hz
  6. Apr 30, 2013 #5


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    Staff: Mentor

    In reality, that second fork must have a frequency of 297Hz or 303Hz, it can't have both fundamentals simultaneously. On the data given for this part of the question, we can't determine which of those two frequencies it does have.

    So the next part resolves to: what must have been done to bring about a beat frequency of just 1Hz?
  7. Apr 30, 2013 #6
    I really don't get it!! >.< this is the only concept I am having a hard time understanding even when the teacher tries to explain it!!! May you please show me how you would do it! Thank you for your time.
  8. Apr 30, 2013 #7
    Maybe this will help: You have determined that the unknown tuning fork has a frequency of either 297 or 303 based on the 3 Hz beat note. Now the problem is how do you determine which of these two frequencies is correct. In your first statement, you say that if you add Plasticine to the fork, the frequency will lower. So, if you add the plasticine to the fork what will happen to the beat note depending on whether the unknown frequency is 297 or 303 hz.
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