1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Resonant Frequency and speed of sound

  1. Aug 26, 2014 #1
    1. Hollow tube chimes are made of metal and are open at each end. One chime is 0.54m long.

    -If the speed of sound is 346m/s, what is the frequency of sound produced by the third resonant length?

    -What would happen to the frequency of sound produced by the third resonant length if the chime were shorter?





    3. I'm having a hard time with this question, but here's my attempt:

    Info: 0.54m, Speed of sound=346m/s
    Half of one wavelength is the length of the chime.
    λ=0.54m*2
    λ=1.08m
    Find frequency:
    v=ƒ*λ
    346m/s=ƒ*1.08m
    ƒ=346/1.08
    ƒ=320Hz
    Find the third resonant length:
    L3=5λ/4
    L3=5(1.08)/4
    L3=1.35m
    Find frequency at this length:
    ƒ=v/λ
    ƒ=346m/s/1.35
    =256Hz
    3rd resonance frequency should be around 960Hz
     
  2. jcsd
  3. Aug 27, 2014 #2

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    L3 is still the length of the pipe, so ##\lambda## is a lot smaller than the 1.08 m you use...

    The 5/4 isn't correct either: both ends are open
     
  4. Aug 27, 2014 #3

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    From the information given, I suppose you are meant to solve the problem like the OP did.

    But in real life the frequency of a hollow tube chime depends on the vibration of the tube bending like a beam, not on the length of the air column inside.
     
  5. Aug 27, 2014 #4
    I've solved it myself. It's actually quite simple, I was using the wrong equation for resonant frequency.

    Info: 0.54m, Speed of sound=346m/s
    Half of one wavelength is the length of the chime.
    λ=0.54m*2
    λ=1.08m
    Use first resonant frequency equation:
    F1=v/λ
    F1=346/1.08
    =320Hz
    Now multiply the first resonant length frequency by 3 to achieve the third resonant length frequency.
    320*3=960Hz.
     
  6. Aug 27, 2014 #5

    BvU

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Well done.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Resonant Frequency and speed of sound
Loading...