💨 Acoustic Waves & Thermodynamics
Speed of Sound in Air & Mediums Calculator
Compute acoustic phase velocity ($c = \sqrt{\gamma R T / M} \approx 331.3 \sqrt{1 + T/273.15}\text{ m/s}$) across air temperatures and various gaseous, liquid, and solid media.
💨 Air at 20°C (343.2 m/s)
❄️ Air at 0°C (331.3 m/s)
💧 Pure Water (1,482 m/s)
🌊 Seawater (1,522 m/s)
🎈 Helium Gas (965 m/s)
🔩 Structural Steel (5,960 m/s)
Temperature & Medium
Speed of Sound (c)
343.2 m/s
1 km Travel Time
2.91 seconds
1 Mile Travel Time
4.69 seconds
Lightning Rule
~3 sec / km
💡 Thermodynamic Gas Law:
$$c = 331.3 \times \sqrt{1 + \frac{20}{273.15}} = 331.3 \times 1.036 = 343.2\text{ m/s}$$
The Physics of Acoustic Propagation
In an ideal gas, sound waves propagate adiabatically without heat exchange:
$$c = \sqrt{\frac{\gamma R T}{M}} = \sqrt{\frac{\gamma k_B T}{m}}$$
- Air Heat Capacity Ratio ($\gamma$): $\gamma = 1.400$ for diatomic air ($N_2, O_2$).
- Molar Mass of Air ($M$): $0.028964\text{ kg/mol}$.
- Lightning Flash Rule: Count seconds between flash and thunder, divide by 3 for distance in kilometers (or divide by 5 for miles).