Talk:Shock wave

In supersonic flows ...

The section on supersonic flows contains the sentence "Shock waves form when the speed of a fluid changes by more than the speed of sound" which can't be right because it compares a change in speed with a speed. I assume what is meant is "speed of a fluid IS more than the speed of sound" but I don't want to edit an article on a subject I don't understand. oldrider (talk) 23:14, 12 January 2017 (UTC)

The phrase "shock of type 1"

is used but not defined. oldrider (talk) 23:17, 12 January 2017 (UTC)

Photo 2

USS Iowa firing a broadside during training exercises in Puerto Rico, 1984. Circular marks are visible where the expanding spherical atmospheric shockwaves from the gun firing meet the water surface.

I don't believe these patterns to be caused by the intersection of shock waves w/ the surface of the water as that would be a conic section basically in reverse of what is shown here. This appears to be a subsonic propagation or pressure wave moving at below Mach 1. Longinus876 (talk) 13:42, 11 December 2019 (UTC)

The projectiles would trail a conical shock wave which would intersect the water surface (roughly) as a moving parabola. The expansion of the air inside the cannon creates an expanding spherical wave originating at the cannon tip, which intersects the water surface (roughly) as a circle. This wave is definitely supersonic here. A sonic (Mach 1) wave is basically a shock wave in the limit where it is reversible and there is no energy dissipation involved. Such a wave would be unable to disturb the water surface, by definition. As the supersonic spherical wave expands, it becomes weaker and slower and ultimately becomes a sound wave travelling at the speed of sound. Pressure cannot propagate slower than the speed of sound, and so Mach 1 is the hard lower limit on the speed at which that wave will propagate. Ariadacapo (talk) 14:44, 11 December 2019 (UTC)

Ah, correct. I was thinking, wrongly, of a supersonic projectile which this was not. The hard edge on the pattern tells a story in itself. Very interesting to me. Thank you for your correction. Where would we all be without a little help from our friends,,, or a shove? Thanks also for the instant response.Longinus876 (talk) 22:07, 11 December 2019 (UTC)

What is the temperature in the 200 nm thick film of the shockwave?

Mentioned are that in the shockwave, the pressure is x25 atmospheric pressure, the thickness of the shockwave film is 200 nm and it is mentioned the temperature increase are what makes shockwaves characteristics and to understand how the ram jet engine works, but I can't find what is the temperature in that film. Thy, SvenAERTS (talk) 13:13, 24 June 2022 (UTC)

Video with very loud & sudden sound, could be dangerous, removed for the moment

I have just played a video that was in this article; it was immediately after the two pictures near the beginning of the article.

The sound was very loud and sudden. The yogurt I was eating almost flew out of my hands, rather it did shake loose from my hands but I managed to catch it. If I was holding a hot drink I would probably have scalded myself. There are many scenarios where the effect could have been serious.

If wearing headphones it might have been damaging to hearing.

I have removed the video from the article, at least for the moment.

This is the code I have removed (I have not included the double square brackets to lessen the chance of someone playing it accidentally):

File:Над Челябинской областью прошел метеоритный дождь.webm|thumb|right|The shockwave from the Chelyabinsk meteor that rocketed across the Russian morning sky on 15 February 2013

The video displays a length of 18 seconds.

I would like to point out that I have not this reaction to any other sound I have ever heard, on TV/film or in real life.

Maybe it could go back in with a reduction in volume and/or a very clear warning and/or needing an extra click to actually play it. I do not know the appropriate way of going about this.

FrankSier (talk) 20:39, 22 November 2024 (UTC)