Why soldiers go out of step while crossing abridge?
Answers
Answer:That’s basically because of energy propagation and the harmonic oscillator principle.
In this case the energy released by the soldier's feet propagates through the bridge and since they are all marching at the same frequency, the bridge absorbs all that energy and it can become a really big harmonic oscillator.
That means the bridge would vibrate like a really big guitar string, and if the soldiers kept marching at the same frequency, the vibration would increase until a theoretical point where it the bridge would collapse.
This happened once in the Angers Bridge incident, in 1850. Now a days, however, it would take a really big (and fragile) bridge and a really big army to put the bridge down that way, since some of that energy is lost during propagation.
Explanation: