2007-09-28 16:33:24 · 7 answers · asked by kntagler 1 in Science & Mathematics ➔ Physics
Marching soldiers do break step when marching on a bridge and yes, that is a requirement and probably laid down in some regulation.
A constant vibration can create a resonance frequency; if that resonance frequency matches that of the bridge then it can be enough to break it. Think of a resonance frequency as the “sweet spot.” If you hit the ball with a tennis racket in the sweet spot then it goes farther and faster, the same it true with a golf club. If you hit the sweet spot on a bridge then the normal vibrations build up on each other and disaster is the result.
The classic engineering example is the Tacoma Narrows Bridge which didn’t account for the wind load in the straights and the wind tore it apart, before that happened the bridge vibrated so much and so strongly that a man trying to walk on the bridge fell down.
For more information on resonance frequency see this Wikipedia article: http://en.wikipedia.org/wiki/Resonance_frequency
It also has a link to the Tacoma Narrows Bridge failure.
2007-09-28 16:47:12 · answer #1 · answered by Dan S 7 · 1⤊ 0⤋
To avoid stressing the bridge excessively... if they march in step, there's a chance that their steps will coincide with the resonant frequency of the bridge and cause possibly dangerous amplified shaking of the whole structure.
more explanations on the link below
p.s. 3rd year sci hi ka??
2007-09-28 16:42:16 · answer #2 · answered by Frances 2 · 1⤊ 0⤋
The step is a regularly enlarging force with period X. The bridge has its own period Y. When X=Y, the amplitudes of bridges waves and the force sum:
A1+B1=A2
A2+B2=A2+B1=2A1+B1
A3+B3=3A1+B1
A - amplitude of bridge
B - amplitude of force
Look for more scientific exploration of resonance in en.wikipedia.org .
2007-09-28 16:46:02 · answer #3 · answered by おぁな 2 · 0⤊ 0⤋
Breakstep
2016-10-15 23:55:20 · answer #4 · answered by eaford 4 · 0⤊ 0⤋
Because they dont want the bridge to vibrate in time to their steps and thus fail.
2007-09-28 16:37:37 · answer #5 · answered by Anonymous · 2⤊ 0⤋
to avoid the possibility matching the resonant frequency of the bridge to induce damaging harmonic motion of the bridge. search the internet, you might find a video of the tacoma narrows bridge (although it wasn't marching)
2007-09-28 16:39:24 · answer #6 · answered by Anonymous · 1⤊ 0⤋
i think it maybe due to the fact that while they march together,the bridge tends to break under excess weight lol i think so.
2007-09-28 16:37:11 · answer #7 · answered by 2008 2 · 0⤊ 4⤋