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

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

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.

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

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

Question 3

When a drummer hits the drum skin and the membrane first moves outward, then quickly back inward, what happens to the tiny air particles right in front of the drum skin during each part of this motion?

Accepted Answer

They are first pushed together (compression) and then pulled apart (rarefaction).

Answer

They first move away from the drum and then stay away, never returning.

Answer

They get hotter when the drum moves outward and colder when it moves inward.

Answer

They stay still while the drum vibrates.

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 drummer hits the drum skin and the membrane first moves outward, then quickly back inward, what happens to the tiny air particles right in front of the drum skin during each part of this motion?

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