Calculating the Sound of Moving Objects?

  • Context: Undergrad 
  • Thread starter Thread starter Ultros88
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Discussion Overview

The discussion revolves around the physics and mathematics involved in calculating the sound produced by moving objects, particularly in the context of using sound to influence motion, such as spinning a pinwheel. The conversation touches on concepts from aeroacoustics and the feasibility of using sound in mechanical applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Ultros inquires about the branches of physics and mathematics relevant to sound produced by moving objects and the possibility of using sound to control motion.
  • One participant suggests aeroacoustics as a relevant field for this inquiry.
  • Another participant expresses concern that Ultros's idea resembles a perpetual motion machine, which is generally dismissed in the forum.
  • Ultros clarifies that the intention is not to create a perpetual motion machine but to explore sound control over a pinwheel.
  • Participants discuss the concept of perpetual motion, referencing its violation of thermodynamic laws and the classification of perpetual motion machines.

Areas of Agreement / Disagreement

There is no consensus on the feasibility of using sound to control motion, and participants express differing views on the concept of perpetual motion, with some dismissing it outright while others engage in a deeper exploration of its implications.

Contextual Notes

Participants reference the need for a mechanical engineering background to fully understand the complexities involved in the proposed ideas, indicating a potential limitation in the discussion's technical depth.

Ultros88
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Hi, I was wondering what branches of physics and mathematics deals with calculating the type of sound produced when various shaped objects move in the air at relatively slow speeds. Specifically I was wondering if it would be possible to move an object, say to spin a pin wheel, by using a very sensitive microphone to pick up the sound it makes whilst moving and then applying that sound at that location with a speaker. Plus, does anyone know where I can find out more about the fact that a light piece of cardboard will be attracted to a vibrating tuning fork.

Thanks,
Ultros
 
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Aeroacoustics is your best bet.

It sounds like you are trying to form some kind of perpetual motion machine by using the sound through an amplifier to further propel the device. Is this so?
 
Please note: perpetual motion is crackpottery and we don't allow crackpottery here.

Please note also: amplifiers require external power to drive speakers.
 
Garvin,
Thanks for pointing me to aeroacoustics. I wasn't really thinking about perpetual motion just wondering if I could use sound to control the motion of a pinwheel. It looks like I'll have to be pretty far along in a mechanical engineering degree to figure everything out.

Waters,
Show me why you think the universe isn't perpetual motion.
 
Ultros88 said:
Waters,
Show me why you think the universe isn't perpetual motion.

Well, because it will run down and stop.
 
Ultros88 said:
Show me why you think the universe isn't perpetual motion.
Besides what was already said, you need to understand what is actually meant when someone says "perpetual motion". There are three types of perpetual motion machines, one for each of the laws of thermodynamics they violate:

http://en.wikipedia.org/wiki/Perpetual_motion#Classification
 

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