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Homework Help: Standing Waves help 30 mins left.

  1. Apr 26, 2005 #1
    Standing Waves help!!!! 30 mins left.

    Hello everyone who's here, so far I've been doin great on waves, but what the heck is standing eave?

    Here is a problem that I kinda get, but not completely:

    Two strings, with the same mass/length m oscillate with the same frequency f=2.00 Hz. The first string has length L1, tension T1 and vibrates in the fundamental mode (n=1). The second string has length L2, tension T2 and vibrates in the third harmonic (n=3). Assuming L2=2.30 L1:

    a) What is the ratio T1/T2?

    b) What would be the frequency of the second string if it oscillates in the mode n=1?

    what the hell is fundamental mode?
    please help, or at least give hints,
    thanks a lot
  2. jcsd
  3. Apr 26, 2005 #2
    well it's kinda late now, and i got the answers here:

    1) 1.70
    2) 0.667 Hz

    Can anyone tell me how to get them at least so i know how to do them on the test?? (formulas may be)???
  4. Apr 26, 2005 #3
    Main fomulae:

    L= (2n-1)(wavelength)/4

    and velocity=(frequency)(wavelength)

    where L=length of string
  5. Apr 26, 2005 #4
    are u saying to find wavelength first?
    what about the tension?
  6. Apr 26, 2005 #5


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    The speeds of the waves are equal to sqrt(tension/mass per unit length). Since the masses are the same, ratio of speeds will be the square root of the ratio of tensions.
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