Editing Resonance (section)

== Disadvantages ==

A column of soldiers marching in regular step on a narrow and structurally flexible bridge can set it into dangerously large [[amplitude]] [[oscillation]]s. On April 12, 1831, the [[Broughton Suspension Bridge]] near [[Salford, England]] collapsed while a group of British soldiers were marching across.<ref name="Bishop">{{cite book |author=Bishop, R.E.D. |title=Vibration |edition=Second |publisher= Cambridge University Press, London |year=1979}}</ref> Since then, the British Army has had a standing order for soldiers to break stride when marching across bridges, to avoid resonance from their regular marching pattern affecting the bridge.<ref name="MEN">{{cite news |title=Broughton Bridge is falling down! |last=Smith |first=Alan |date=12 April 1975 |work=Manchester Evening News }}</ref><ref>{{cite book |last=Braun |first=Martin |title=Differential Equations and Their Applications: An Introduction to Applied Mathematics |year=1993 |edition=4 |page=175 |url=https://books.google.com/books?id=USWV3PP3b08C&q=Differential+Equations+and+Their+Applications:+An+Introduction+to+Applied+Mathematics |isbn=0-387-97894-1 |access-date=30 May 2009 |publisher=Springer-Verlag |location=New York}}</ref>

Vibrations of a motor or engine can induce resonant vibration in its supporting structures if their [[natural frequency]] is close to that of the vibrations of the engine. A common example is the rattling sound of a bus body when the engine is left idling.

Structural resonance of a suspension bridge induced by winds can lead to its catastrophic collapse. Several early suspension bridges in [[Europe]] and [[United States]] were destroyed  by structural resonance induced by modest winds. The collapse of the [[Tacoma Narrows Bridge (1940)|Tacoma Narrows Bridge]] on 7 November 1940 is characterized in physics as a classic example of resonance.<ref name="Forbes">{{cite news |last1=Siegel |first1=Ethan |author1-link=Ethan Siegel |title=Science Busts The Biggest Myth Ever About Why Bridges Collapse |url=https://www.forbes.com/sites/startswithabang/2017/05/24/science-busts-the-biggest-myth-ever-about-why-bridges-collapse/?sh=41b3a01a1f4c |access-date=3 January 2021 |work=[[Forbes]] |date=24 May 2017}}</ref> It has been argued by [[Robert H. Scanlan]] and others that the destruction was instead caused by [[aeroelasticity#Flutter|aeroelastic flutter]], a complicated interaction between the bridge and the winds passing through it—an example of a [[self oscillation]], or a kind of "self-sustaining vibration" as referred to in the nonlinear theory of vibrations.{{sfn|Billah|Scanlan|1991|p=}}