Velocity of Sound in Pure Water to Millimeter per Hour

The speed of sound in pure water at 20°C is approximately 1,482.7 m/s, significantly faster than in air due to water's higher density and bulk modulus.

Depends on water temperature, salinity, and pressure. At 20°C, pure water: ~1,483 m/s. Varies with depth and location.

To km/h: × 3.6. To ft/s: × 3.281. 1,483 m/s = 5,339 km/h = 3,317 mph.

Sonar (submarine detection, fish finding), ultrasound imaging, underwater communication, and oceanographic measurements.

Sound in water travels ~4.3× faster than in air. Whales can communicate over hundreds of km using this. SOFAR channel enables even longer distances.

Assuming sound speed in water equals sound in air — it's much faster. Also, forgetting temperature dependence.

~1,500 m/s in water (rule of thumb). 4–5× faster than in air. Increases with temperature, salinity, and depth.

Millimeter per hour measures extremely slow movements in millimeters over an hour. Used for minute geological and material changes.

1 mm/h = 0.001 m/h = 0.0000001 km/h = 0.000000278 m/s.

To m/s: ÷ 3,600,000. To cm/h: ÷ 10. To m/h: ÷ 1,000.

Cave formation rates (stalactite/stalagmite growth), extremely slow material creep, and long-term geological monitoring.

Stalactite growth: 0.1–1 mm/h in active caves. Human hair growth: ~0.015 mm/h. Fingernail growth: ~0.004 mm/h.

Using for anything except the slowest processes. Confusing with mm/min (60× faster).

1,000 mm/h = 1 m/h. Extremely specialized unit. Think geological time scales.