Editing Shock wave (section)

{{short description|Propagating disturbance}}
{{redirect|Shockwave}}
{{redirect|Bombshock|the Transformers character|Micromasters}}
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[[Image:Schlierenfoto Mach 1-2 Pfeilflügel - NASA.jpg|thumb|right|[[Schlieren photography|Schlieren photograph]] of an attached shock on a sharp-nosed [[supersonic]] body]]
[[Image:Uss_iowa_bb-61_pr.jpg|thumb|right|[[USS Iowa (BB-61)|USS ''Iowa'']] firing at [[Broadside (naval)|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.]]

In physics, a '''shock wave''' (also spelled '''shockwave'''), or '''shock''', is a type of propagating disturbance that moves faster than the local [[speed of sound]] in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium, but is characterized by an abrupt, nearly discontinuous, change in [[pressure]], [[temperature]], and [[density]] of the medium.<ref>{{Citation
|last = Anderson | first = John D. Jr.| title = Fundamentals of Aerodynamics | orig-year = 1984 | edition = 3rd| publisher =  [[McGraw-Hill|McGraw-Hill Science/Engineering/Math]] |date=January 2001| isbn = 978-0-07-237335-6 }}</ref><ref>Zel'Dovich, Y. B., & Raizer, Y. P. (2012). Physics of shock waves and high-temperature hydrodynamic phenomena. Courier Corporation.</ref><ref>Landau, L. D., & Lifshitz, E. M. (1987). Fluid Mechanics, Volume 6 of course of theoretical physics. Course of theoretical physics/by LD Landau and EM Lifshitz, 6.</ref><ref>Courant, R., & Friedrichs, K. O. (1999). Supersonic flow and shock waves (Vol. 21). Springer Science & Business Media.</ref><ref>Shapiro, A. H. (1953). The dynamics and thermodynamics of compressible fluid flow, vol. 1 (Vol. 454). Ronald Press, New York.</ref><ref>Liepman, H. W., & Roshko, A. (1957). Elements of gas dynamics. John Willey & Sons.</ref>

For the purpose of comparison, in [[supersonic speed|supersonic]] flows, additional increased expansion may be achieved through an [[expansion fan]], also known as a [[Prandtl–Meyer expansion fan]]. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The [[sonic boom]] associated with the passage of a supersonic aircraft is a type of sound wave produced by [[Wave interference|constructive interference]].

Unlike [[soliton]]s (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distance. When a shock wave passes through matter, [[energy]] is preserved but [[entropy]] increases. This change in the matter's properties manifests itself as a decrease in the energy which can be extracted as work, and as a [[wave drag|drag force on supersonic objects]]; shock waves are strongly [[irreversible process]]es.