Which statement best describes sound propagation in a medium?

Which statement best describes sound propagation in a medium?

• A. A Molecule Travels From One End To Another
• B. A Molecule Does Not Vary Its Position As A Sound Wave Travels
• C. A Molecule Oscillates Back And Forth To Propagate Sound Waves But Does Not Move From One End Of The Medium To Another
• D. Each Molecule Expands And Contracts To Propagate A Sound Wave Through A Medium

Answer: (C)

Sound travels by energy moving through the medium via tiny vibrations of its particles. Each molecule doesn’t ride the wave from one end of the medium to the other; instead, it wiggles back and forth around its resting position as neighboring molecules push and pull on it. This back-and-forth motion transfers energy through successive interactions, creating regions of compression and rarefaction that travel through the material. That’s why the best description is that a molecule oscillates back and forth to propagate sound waves but does not move along the length of the medium. The idea of a molecule traveling from end to end would imply matter is carried along with the wave, which isn’t how sound works. Saying a molecule does not vary its position is inconsistent with the passing wave, since molecules do move slightly as the wave passes. And molecules don’t literally expand and contract themselves; the medium’s density and pressure change as the wave moves, not the size of the individual molecules.

Sound travels by energy moving through the medium via tiny vibrations of its particles. Each molecule doesn’t ride the wave from one end of the medium to the other; instead, it wiggles back and forth around its resting position as neighboring molecules push and pull on it. This back-and-forth motion transfers energy through successive interactions, creating regions of compression and rarefaction that travel through the material.

That’s why the best description is that a molecule oscillates back and forth to propagate sound waves but does not move along the length of the medium. The idea of a molecule traveling from end to end would imply matter is carried along with the wave, which isn’t how sound works. Saying a molecule does not vary its position is inconsistent with the passing wave, since molecules do move slightly as the wave passes. And molecules don’t literally expand and contract themselves; the medium’s density and pressure change as the wave moves, not the size of the individual molecules.