What factors affect the frequency of harmonics in a soda bottle?

In summary, the conversation discusses the frequency of the next harmonic heard when blowing across the open end of a soda bottle and how it is affected by the strength of the blow. It is mentioned that the speed of sound and the speed of the molecules in the air play a role in the frequency of the next harmonic. The concept of a Helmholtz resonator is also brought up and a link to an article is shared.
  • #1
bahtiyar
19
1
I saw a question
"If you blow across the open end of a soda bottle and produce a tone of 250 Hz, what will be the frequency of the next harmonic heard if you blow much harder?"
the answer is 750 Hz
but I'm curious about "if you blow much harder" part, is it really depends on how much harder you blow or something else?
 
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  • #2
Do the experiment and you'll be the expert !
 
  • #3
When you run the experiment check how the frequency changes. Jumping an octave is what I'd expect (from 250 Hz to 500 Hz).
 
  • #4
I think the point is that it is closed at one end and open at the other; there is a node at the closed end and an antinode at the open end, so it goes from 1/2 wavelength to 3/2 wavelength.
 
  • #5
mjc123 said:
I think the point is that it is closed at one end and open at the other; there is a node at the closed end and an antinode at the open end, so it goes from 1/2 wavelength to 3/2 wavelength.
Didn't give that any thought. I believe you have the right of it.
 
  • #6
isn't that about the speed of sound, if it is right how it much harder blowing effect on it. What is the logic here can anyone explain?
 
  • #7
bahtiyar said:
isn't that about the speed of sound
The speed of sound is near 750 MPH, 750 Hz is oscillations per second...
 
  • #8
bahtiyar said:
isn't that about the speed of sound, if it is right how it much harder blowing effect on it. What is the logic here can anyone explain?
Think about the speeds of the molecules which are needed for each harmonic mode.
 
  • #9
I think this is pretty complicated, since a bottle like that is an example of a Helmholtz resonator. The column of air in the neck of the bottle is acting like the piston, and the air in the main portion of the bottle is acting like the spring. The basic linear theory is pretty simple - it is explained in basic sophomore level physics texts (eg Electromagnetic Vibrations, Waves and Radiation by Bekefi and Barrett). The harmonics are not as easy for me to understand. A quick google search did find an article that may be of interest:
http://iopscience.iop.org/article/10.1088/1361-6552/aa532b/meta

Jason
 
  • Like
Likes bahtiyar
  • #10
jasonRF said:
I think this is pretty complicated, since a bottle like that is an example of a Helmholtz resonator. The column of air in the neck of the bottle is acting like the piston, and the air in the main portion of the bottle is acting like the spring. The basic linear theory is pretty simple - it is explained in basic sophomore level physics texts (eg Electromagnetic Vibrations, Waves and Radiation by Bekefi and Barrett). The harmonics are not as easy for me to understand. A quick google search did find an article that may be of interest:
http://iopscience.iop.org/article/10.1088/1361-6552/aa532b/meta

Jason
thank you
the video on the page clearly shows which harmonic occurs depend on the speed of air that we blow. I can't reach the article it requires purchase the article but video was enough for me
 

1. What are harmonics on a soda bottle?

Harmonics on a soda bottle are sound waves or vibrations that are created when air is blown across the opening of a partially filled soda bottle. These vibrations produce a musical tone that can be changed by altering the amount of liquid in the bottle or the strength of the air blown across the opening.

2. How do harmonics on a soda bottle work?

The sound produced by a soda bottle is created through a phenomenon known as resonance. When air is blown across the opening of the bottle, it creates a standing wave within the bottle. This standing wave is made up of multiple harmonics, or multiples of the fundamental frequency, which combine to produce the unique sound of the soda bottle.

3. What factors affect the pitch of the sound produced by a soda bottle?

The pitch of the sound produced by a soda bottle can be affected by the amount of liquid in the bottle, the size and shape of the bottle, and the strength of the air blown across the opening. The more liquid in the bottle, the lower the pitch will be. A larger and more cylindrical bottle will also produce a lower pitch compared to a smaller and more conical bottle. Additionally, blowing harder across the opening will produce a higher pitch.

4. Can you create different notes with a soda bottle?

Yes, it is possible to create different notes with a soda bottle by adjusting the amount of liquid in the bottle or the strength of the air blown across the opening. By changing these factors, the harmonics within the standing wave will be altered, resulting in a different pitch or note.

5. Are harmonics on a soda bottle only produced with soda bottles?

No, harmonics can be produced with any type of bottle or container that is partially filled with liquid and has a small opening. Other common examples include wine glasses, beer bottles, and even plastic water bottles. The principle of resonance and the production of harmonics are the same for all of these objects.

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