Why Don't Gases Make a Boom When They Exceed the Speed of Sound?

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SUMMARY

Gases do not produce a "boom" when their molecules exceed the speed of sound due to their small size and dispersed nature. Unlike large objects such as jets that create shock waves and loud noises upon breaking the sound barrier, gas molecules are constantly colliding and moving randomly, which prevents the formation of a shock wave. This fundamental difference in scale and behavior explains the absence of a loud sound from gases exceeding the speed of sound.

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  • Understanding of basic gas laws and molecular behavior
  • Familiarity with sound waves and shock wave formation
  • Knowledge of the concept of the sound barrier
  • Basic principles of thermodynamics
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ssor1
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Hello

My first posting and doubtless it betrays my ignorance :smile:

Doing the basic maths for an ideal gas, I find that the speed of a molecule exceeds the speed of sound through the same gas. I know jets make a terrific 'boom' when they break the sound barrier. Why don't gases go boom? Or have I got the maths wrong? I like to think Nature very kindly chooses to break her own laws rather than let trifling molecules break the sound barrier, which would offend the ears of us more significant particles. Am I right or am I wrong? Any advice would be most welcome :approve:

ssor1
 
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Hello ssor1,

Welcome to the forum and thank you for sharing your thoughts and questions! It's great to see that you're curious and willing to learn more about the behavior of gases.

To answer your question, gases do not produce a "boom" sound when they exceed the speed of sound because they are made up of individual molecules that are very small and spread out. When a jet breaks the sound barrier, it is a large object moving at a high speed and creates a shock wave that produces a loud noise.

On the other hand, gas molecules are so small and spread out that when they exceed the speed of sound, they do not create a shock wave or produce a loud noise. In fact, the molecules are constantly colliding with each other and bouncing off in different directions, so the overall effect is not a loud boom but rather a continuous and random movement.

In short, the scale and behavior of gas molecules are very different from that of a jet breaking the sound barrier, which is why we do not hear a "boom" when gases exceed the speed of sound. I hope this helps to clarify your question. Keep asking and learning, and don't worry about making mistakes - that's how we all learn and grow!
 

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