What exact speed point does shock wave start to appear

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Discussion Overview

The discussion centers on the conditions under which shock waves begin to form, particularly in relation to speed, and explores various definitions and characteristics of shock waves, including sonic booms. It encompasses theoretical explanations, mathematical formulations, and practical examples.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • Some participants suggest that shock waves form when an object travels at or above the speed of sound, with specific reference to sonic booms.
  • Others argue that shock waves can occur whenever air moves faster than the speed of sound relative to the object, emphasizing that there is no fixed speed for shock wave formation.
  • A participant presents a mathematical explanation involving the Doppler effect, indicating that the frequency of sound waves changes based on the speed of the source relative to the speed of sound.
  • Another participant discusses the pressure conditions necessary for shock waves, noting that a peak pressure greater than 1 atm is not a strict requirement for shock wave formation.
  • Some contributions highlight the complexity of shock wave behavior, including the transition from shock waves to regular sound waves and the factors influencing the characteristics of sonic booms.
  • There is mention of the differences in sound produced by various supersonic objects, such as bullets versus aircraft, and how these differences relate to shock wave intensity and propagation.
  • Questions are raised about the relationship between shock waves and blast waves, indicating a potential area for further exploration.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and conditions for shock wave formation, with no consensus reached on a singular definition or explanation. Multiple competing perspectives remain throughout the discussion.

Contextual Notes

Some arguments rely on specific assumptions about pressure and temperature conditions, and the definitions of shock waves may vary among participants. The discussion includes unresolved mathematical aspects and complexities related to the behavior of sound waves in different contexts.

  • #31
Ahh, I seem to have found the paper I had remembered (and it's from one of my professors too, which explains why I saw it in the first place):

http://rd.springer.com/article/10.1007/BF02511381
 
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  • #32
and right on time. I was studying about shock tubes just now and I needed extra examples! xD
Thanks!
 
  • #33
And there we go: Van der Waals gas. I'm not even familiar with that sort of equation of state, but that seems to be about the sort of tomfoolery required to create an expansion shock.
 
  • #34
Correct me if I'm wrong I'm only 15. But doesn't air pressure affect the speed at which is needed to make a cone. If so it would be easier at 50k feet to go faster but you would not created a cone until you reach a higher speed. And vice versa with say. 5k feet.
 
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