MODULE 03
Acoustics
Theory of Sound · Mechanical Waves · Doppler Effect · Resonance · Decibel Scale
Wave Type
Controls
2
0.70
LONGITUDINAL WAVE — PARTICLE SIMULATION
Longitudinal Waves (Sound in Air)
In a longitudinal wave, particles vibrate parallel to the direction of wave propagation. Sound in gases and liquids travels exclusively as longitudinal waves. The particles don't travel with the wave — they oscillate back and forth, creating alternating zones of compression (high pressure, particles close together) and rarefaction (low pressure, particles spread apart).
Compression
High pressure region. Particles pushed together. Increased density.
Rarefaction
Low pressure region. Particles spread apart. Decreased density.
Speed of Sound in Different Media
| Medium | Speed | Note |
|---|---|---|
| Air (0°C) | 331 m/s | Dry air at 0°C |
| Air (20°C) | 343 m/s | Standard room temperature |
| Fresh Water | 1482 m/s | At 20°C |
| Sea Water | 1531 m/s | At 20°C, 35‰ salinity |
| Steel | 5960 m/s | Longitudinal wave |
| Glass | 5640 m/s | Borosilicate |
| Wood (Oak) | 3850 m/s | Along grain |
| Rubber | 60 m/s | Soft rubber |