What Causes the Pitch Changes in a Spinning Twirler Toy?

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Homework Help Overview

The discussion revolves around the physics of a child's toy known as a twirler, which consists of a tube spun in a circular motion. Participants are exploring the relationship between the rotation rate of the twirler and the resulting sound pitch, as well as the underlying resonance effects and sound source dynamics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are considering the effects of the tube's open or closed ends on sound pitch and resonance. There is discussion about how pressure changes during twirling might influence sound speed and resonant frequency. The Doppler effect is also mentioned in relation to the movement of the sound source relative to an observer.

Discussion Status

The conversation reflects a mix of attempts to clarify concepts and express frustration over communication issues. Some participants are questioning the clarity of previous statements and the relevance of certain details, while others are attempting to formulate a more coherent explanation.

Contextual Notes

There appears to be some confusion regarding the terminology used to describe the observer's relationship to the sound source, which has led to a breakdown in communication among participants.

hulkster
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Standing Wave/ Resonanace problem PLEASE HELP!

Ok. I've tried to answer this problem so many times now, but I just can't get it. Here it is:

A child's toy called a twirler, consists of a tube (like a hose, which is spun
in a circle above one's head. It is noted that at certain rates of rotation,
sounds of definite pitch are heard. What is the source of the sound? what are
the resonance effects? What is the relationship between pitch and rate of
rotation...?


Thank You in advance
 
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hulkster said:
Ok. I've tried to answer this problem so many times now, but I just can't get it. Here it is:

A child's toy called a twirler, consists of a tube (like a hose, which is spun
in a circle above one's head. It is noted that at certain rates of rotation,
sounds of definite pitch are heard. What is the source of the sound? what are
the resonance effects? What is the relationship between pitch and rate of
rotation...?


Thank You in advance

It will make a difference in the pitch if the tube is open on both ends or closed on the end being held. I assume it is open at both ends. You need to look at standing waves in a pipe, and think about two possible effects from twirling the tube. 1) Will the pressure in the tube change when it is being twirled? If it does, that will affect the speed of sound in the tube and that will affect the resonant frequency. 2) The doppler effect. The sound source will be moving relative to an observer hearing the sound from a tube someone else is twirling.
 
OlderDan said:
The sound source will be moving relative to an observer hearing the sound from a tube someone else is twirling.
Woah. We're sorry, the English language has sustained a major back-injury and will be out for the duration the the game.
 
DaveC426913 said:
Woah. We're sorry, the English language has sustained a major back-injury and will be out for the duration the the game.

The sound source will be moving relative to an observer who is hearing the sound that is coming from a tube that someone else is twirling.

Can you understand it now? Did you really need those extra words?
 
OlderDan said:
The sound source will be moving relative to an observer who is hearing the sound that is coming from a tube that someone else is twirling.

Can you understand it now? Did you really need those extra words?
No. Less. :biggrin:

"The sound source will be moving relative to an external observer."
 
DaveC426913 said:
No. Less. :biggrin:

"The sound source will be moving relative to an external observer."

External to what?? The tube?

This is ridiculous and you know it. I'm finished with the subject.
 
OlderDan said:
External to what?? The tube?

This is ridiculous and you know it. I'm finished with the subject.

You're being deliberately obtuse, and you seem to be a bit defensive. I don't think that's really helping hulkster.

When I have more time I'll try to compose an answer.
 

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