Cosmic Velocity - Third to Velocity of Sound in Sea Water (20°C, 10m depth)

The third cosmic velocity is approximately 16,700 m/s (16.7 km/s), the minimum speed to escape the Sun's gravity from Earth's orbital position.

v₃ = √(v_sun² - v_Earth²) where v_sun is solar escape velocity from Earth's orbit. Approximately 16.7 km/s relative to Earth.

To km/h: × 3,600. To mph: × 37,282. 16.7 km/s = 60,120 km/h = 37,344 mph.

Voyager missions, future interstellar probes, and calculations for leaving the solar system.

Voyager 1: ~17 km/s relative to Sun (achieved via Jupiter gravity assist). Parker Solar Probe: 163 km/s peak (but toward Sun, not away).

Thinking Voyager was launched at 16.7 km/s — it used gravity assists. Also, confusing with speed needed to escape from Sun's surface (618 km/s).

~17 km/s to leave the solar system from Earth's orbit. Voyagers achieved this with gravity assists from planets.

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.