Cosmic Velocity - Third to Velocity of Sound in Pure Water

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 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.