Cosmic Velocity - Third to Foot per Hour

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.

Foot per hour measures distance in feet traveled over one hour. Used for very slow movements in imperial units.

1 ft/h = 0.000085 m/s = 0.0003048 km/h = 0.3048 m/h.

To ft/s: ÷ 3,600. To mph: ÷ 5,280. To m/s: × 0.000085.

Glacier movement in US studies, very slow industrial processes, and some geological measurements.

Some glaciers move at 50–500 ft/h. Very slow conveyor systems might use this unit.

Confusing with ft/min (60× faster) or ft/s (3,600× faster).

5,280 ft/h = 1 mph. Extremely slow. Rarely used outside specialized contexts.