This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics articles
This article is within the scope of the Aviation WikiProject. If you would like to participate, please visit the project page, where you can join the project and see lists of open tasks and task forces. To use this banner, please see the full instructions.AviationWikipedia:WikiProject AviationTemplate:WikiProject Aviationaviation articles
This article has been given a rating which conflicts with the project-independent quality rating in the banner shell. Please resolve this conflict if possible.
This article has not yet been checked against the criteria for B-class status:
Referencing and citation: not checked
Coverage and accuracy: not checked
Structure: not checked
Grammar and style: not checked
Supporting materials: not checked
To fill out this checklist, please add the following code to the template call:
I am amazed that this blunder has survived so long. A shock wave always travels at the speed of sound in the medium through which it propagates. That is the definition of the speed of sound: it is the speed that a disturbance of pressure or density propagates through a meduim [1].
Shock waves may be generated at a greater speed - e.g. the one at the front of a supersonic jet (which propagates from the jet to the observer at Mach 1.0), or the one at the blast front of an explosion, which may be generated at hypersonic speeds whilst the detonation is in progress, but, on completion of the detonation (after milliseconds) detach from the decaying detonation and propagates at Mach 1.0
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)[reply]
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)[reply]
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)[reply]
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)[reply]
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)[reply]