Velocity of Sound in Sea Water (20°C, 10m depth) to Foot per Minute

The speed of sound in seawater at 20°C and 10 meters depth is approximately 1,522 m/s, varying with temperature, salinity, and pressure.

Complex function of T, S, P. Mackenzie equation: c ≈ 1,449 + 4.6T - 0.055T² + 0.00029T³ + (1.34-0.01T)(S-35) + 0.016z. Typical: ~1,500 m/s.

To km/h: × 3.6. To ft/s: × 3.281. 1,522 m/s = 5,479 km/h = 3,404 mph.

Naval sonar, commercial ship echo sounders, underwater positioning systems, and marine seismic surveys.

Sound speed increases ~1.3 m/s per °C, ~1.3 m/s per PSU salinity, and ~1.7 m/s per 100m depth. SOFAR channel at ~1000m depth traps sound for thousands of km.

Using a single constant — sound speed in the ocean varies significantly with depth and location. Always measure or calculate for local conditions.

~1,500 m/s is a good approximation. Remember: warmer, saltier, deeper = faster sound. Critical for accurate sonar ranging.

Foot per minute measures distance in feet traveled in one minute. Common in US industrial and HVAC applications.

1 ft/min = 0.00508 m/s = 0.01829 km/h = 0.3048 m/min.

To ft/s: ÷ 60. To m/s: × 0.00508. To mph: ÷ 88.

HVAC duct air velocity (600–2,000 fpm), conveyor belts (50–300 fpm), elevator speeds (200–1,500 fpm), and escalators (90–120 fpm).

Typical HVAC duct: 800–1,200 fpm. High-rise elevator: 1,000 fpm. Airport moving walkway: 140 fpm.

Confusing ft/min with ft/s — ft/min is 60× slower. Mixing fpm with mph.

60 ft/min = 1 ft/s. ~88 ft/min = 1 mph. Essential for HVAC calculations in the US.