Physics GRE Discussion Forums

I was watching some slow motion footage of jet air planes breaking the sound barrier...I noticed that the wind enveloped over the wings and this "wind wake" continued to move toward the back of the jet until it folded in on itself and the "wind wake" caused a popping noise. I noticed what was really happening.

This is what was really happening:

The jet was pushing through the air so fast it caused the wind to clap. Just like a bullwhip does.

I studied a bullwhip action and found out it does not clap against itself...it pushes through the air so fast it causes the wind to clap. Like when one wave on the water crashes into another wave on the water...and we hear the "crash".

In fact, I bet I can take just about anything...like a towel...and make a loud popping noise by "popping it".

Cracking a bullwhip is not breaking the sound barrier...it's causing the wind to clap with a piece of leather pushed through the air fast enough.

In both situations, I mean both the jet air plane and the towell or bullwhip...the known variables are simple. We know they are solid objects moving through the air very fast, and they make a loud popping noise.

What we don't know is if this should be called breaking the sound barrier or not.

Maybe when you break the sound barrier there is no new sound at all. But when you break the wind barrier there is a loud popping noise.

Nuimshaan

My night was made by this post . Thank you

This should really make your night...

Have you ever heard of a water boom?

The sound produced when you lay your hand flat on the surface of a pool of water, then quickly push your hand straight down in the water. It goes boom and makes a splash of water go straight up in the air also. I can make a canopener into a good pool spew water like fifteen twenty in the air. And make a nice boom sound too.

Since air is a thinner density version of water...it goes without reason I would have to move something real fast real quick to make the air boom sound and have a plume of air come out.

Like a bullwhip for example. Or a towell. Or a piece of metal moving through the air. It serves to reason that if air was doing the same thing water was doing when something moved fast through it...what we are experiencing is in fact an air pop, and nothing to do with the sound barrier...

If nothings moves that fast through air, there will be NO sonic boom. Let me put it that way.

If something moves that fast through air, it will make a popping noise. Depending on how big it was and how fast it was going when it made the wind pop, the louder the sound will be. Moving fast into that barrier where the wind will pop, will make the sound louder.

A bullwhip is small, moving pretty fast, but only makes a small crackle compared to a large jet doing the same thing.

This says nothing of breaking the sound barrier, rather breaking the wind barrier. It is only after the wind is caused to clap in on itself that a sound is produced...the wind must fold in on itself first or "sonic boom". Therefore it is breaking the wind barrier to cause a sonic boom, not breaking the sound barrier to make a sonic boom...that is wrong.

Nuimshaan.