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Homework Help: More on fundamental frequency

  1. Jan 6, 2005 #1
    A horizontal string of length 1.5 m vibrates with a wave velocity of 1320 m/s at its fundamental freq.

    a. What is the fund. freq.?

    Do I use the formula f_1 = v/4L?

    b. What is the freq. of the 4th overtone and how many nodes and antinodes will it have?

    To find 4th's freq. use f_n = 4*f_1?

    Since this is 4th overtone, are there 6 nodes and 5 antinodes?

    (assuming for 4th 5 positive crests on basic diagram for all situations)

    c. In terms of interference to what do the nodes and antinodes correspond?

    this is conceptual, right?

    nodes - locations where string appears motionless due to destructive interference

    antinodes - where string has greatest displacement due to constructive displacement.

    d. how many g must string be to have a tension of 10^5 N?

    Just use v = sqrt[F/(m/L)]
  2. jcsd
  3. Jan 6, 2005 #2

    Doc Al

    User Avatar

    Staff: Mentor

    No. The general formula is [itex]f_m = m v/2L[/itex].

    The 4th overtone is the 5th harmonic (m = 5 in the above formula).
    Just by accident, this is correct. :smile:

    Right (but that's constructive interference).

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