Question

A sound wave is travelling from East to West. In which direction do the molecules in the air move?
A. East to West
B. West to East
C. North to South
D. South to North

Answer 1

Hint: Here we have to first see how sound waves propagate to get the correct answer.
Sound is a mechanical movement that comes from the acceleration back and forth of the medium objects over which the sound wave travels. The particle's motion is parallel to the direction of the transport of material. This is what characterises longitudinal waves as sound waves in the air.

Complete step by step answer:
In a medium such as air, sound waves function as patterns in energy. They are produced by an object’s acceleration, which induces the acceleration of the air around it. Then the vibrating air allows the human eardrum, which the brain interprets as vibrations, to vibrate.
Longitudinal waves with compressions and rarefactions are sound waves moving across the air. The fragments of air do not vibrate in a transverse manner when sound travels through the air.
If the medium begins to vibrate, the waves spread at the speed of sound away from the source, thereby creating the sound wave. The strain, velocity and displacement of the medium differ in time at a defined distance from the source.
By transferring energy from one molecule to the next one, the sound wave propagates through the medium. So, the molecule’s path and the sound wave would be the same.
Hence, option C is correct.
Therefore, the molecules in the air move from East to West.

Note:Here we have to pay attention in which direction the sound wave is travelling. If the medium begins to vibrate, the waves spread at the speed of sound away from the source, thereby creating the sound wave.