How Sound Waves Travel

Question 1

A tuning fork is struck and its prongs vibrate back and forth. Which description best explains how the air directly in front of the fork changes as the fork vibrates?

Accepted Answer

The air molecules are pushed together, then pulled apart, creating alternating high‑pressure (compression) and low‑pressure (rarefaction) regions.

Answer

All the air molecules move in the same direction away from the fork, forming a steady wind.

Answer

The air molecules spin in tiny circles around the fork, heating the air but not changing pressure.

Answer

Only the molecules that touch the fork vibrate; the rest of the air stays still.

Question 2

Why does sound travel faster through a metal rod than through air, and why can it not travel at all in outer space?

Accepted Answer

Because the particles in a solid are tightly packed, letting each vibration be passed to the next very quickly, and a vacuum has no particles to pass the vibration.

Answer

Because solids are heavier than gases, so vibrations move faster, and in a vacuum sound is present but too quiet to hear.

Answer

Because sound needs magnetic fields to travel, which exist in solids but not in a vacuum.

Answer

Because the temperature inside solids is higher, making sound travel faster, while a vacuum is too cold for sound.

Question 3

When a speaker cone first moves outward and then inward, what happens to the air particles right in front of the cone?

Accepted Answer

First the particles are squeezed together forming a compression, then they spread apart forming a rarefaction, and this pattern repeats.

Answer

First the particles spread apart forming a rarefaction, then they are squeezed together forming a compression, and this pattern repeats.

Answer

The particles only move back‑and‑forth without changing how close they are, so no compression or rarefaction occurs.

Answer

The particles move in tiny circles, creating compression and rarefaction at the same time.

Try three questions

A tuning fork is struck and its prongs vibrate back and forth. Which description best explains how the air directly in front of the fork changes as the fork vibrates?

Why does sound travel faster through a metal rod than through air, and why can it not travel at all in outer space?

When a speaker cone first moves outward and then inward, what happens to the air particles right in front of the cone?

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