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Science · Physical Science
Sound & Mechanical Waves
Sound is a mechanical wave — it needs stuff (a medium) to travel through. Vibrating particles pass the energy along to your ear!
🔊How Sound Travels
A vibration pushes particles into compressions (squished) and rarefactions (spread). That pattern carries the energy all the way to your ear.
Compression — particles squished close together
Rarefaction — particles spread far apart
📈Two Things a Wave Can Do
🔊AMPLITUDE = LOUDNESS
What it isThe height of the wave.
RuleTaller wave → LOUDER sound. Shorter wave → quieter sound.
🥁 a loud drum makes a tall wave
🎵FREQUENCY = PITCH
What it isHow many waves pass each second (measured in Hz).
RuleMore waves → HIGHER pitch. Fewer waves → lower pitch.
🐦 a tiny bird chirps a high pitch
🌌Sound Needs a Medium
🌍 Sound travels through stuff — not nothing!
🪨Through solids (the ground), liquids (water), and gases (air) — sound zooms along.
🚀In outer space there are no particles to vibrate, so space is silent.
🐋Fun fact: sound travels about 4× faster in water than in air!
🔑Key Terms
🌊Mechanical Wave A wave that needs a medium (matter) to travel through.
🧱Medium The material a wave moves through — solid, liquid, or gas.
📊Amplitude The height of a wave — it sets the LOUDNESS.
🎶Frequency How many waves pass per second (Hz) — it sets the PITCH.
🤝Compression A spot where particles are squished close together.
↔️Rarefaction A spot where particles spread far apart.
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Remember: sound is a mechanical wave, so it ALWAYS needs a medium to travel — that's why outer space is totally silent!