Assertion: soldiers are asked to break steps while crossing the bridge.
Reason: The frequency of marching may be equal to the natural frequency of bridge and may lead to resonance which can break the bridge.

Options

A. if both the assertion and reason are true and reson is a true explanation of the assertion.
B. if both the assertion and reason are true but the reason is not the correct explanation of assertion.
C. If the assertion is true but reason is false.
D. If both the assertion and reason are false.

Answer

A

Explanation

If the soldiers while crossing a suspended bridge march in steps, the frequency of marching steps of soldiers may match with the natural frequency of oscillations of the suspended bridge. In that situation resonance will take place, then the aplitude of oscillation of the suspended bridge will increase enormously, which may cause the collapsing of the bridge. to avoid situations the soldiers are advised to go out steps on suspended bridge.