Physics 2005 JAMB Past Questions - Question 35: Marching soldiers crossing a suspension bridge are usually advised to break their steps to avoid damaging the bridge owing to

Correct Answer

D

Explanation

The advice for marching soldiers to break their steps while crossing a suspension bridge is to prevent the phenomenon known as resonance or harmonic motion. Resonance occurs when an external force is applied to a system at just the right frequency, causing the system to vibrate at a larger amplitude. In the case of a suspension bridge, the soldiers' marching steps could potentially match the natural frequency of the bridge, causing it to vibrate with increasing amplitude.

If the soldiers continue to march in unison and the bridge starts to vibrate at its natural frequency due to the regular rhythm of their steps, the oscillations can become more and more pronounced. This can lead to structural damage, and in extreme cases, it could even cause the bridge to collapse.

By breaking their steps and not marching in perfect unison, the soldiers ensure that the forces they apply to the bridge do not match its natural frequency, reducing the risk of resonance. This precaution helps protect the structural integrity of the suspension bridge and ensures the safety of those crossing it.