Cosmic Velocity - Second to Foot per Hour

The second cosmic velocity (Earth's escape velocity) is approximately 11,200 m/s (11.2 km/s), the minimum speed to escape Earth's gravity completely.

v₂ = √(2GM/r) = √2 × v₁ ≈ 11.2 km/s. Exactly √2 times the first cosmic velocity.

To km/h: × 3,600. To mph: × 25,000. 11.2 km/s = 40,320 km/h = 25,053 mph.

Moon missions, Mars missions, deep space probes (Voyager, New Horizons), and any mission leaving Earth's gravity well.

Apollo missions: ~11.2 km/s. Voyager probes: exceeded v₂ to leave solar system. New Horizons: launched at record 16.26 km/s (fastest ever from Earth).

Thinking you need this speed everywhere — you only need it at launch. In space, much less Δv is needed.

~11 km/s to escape Earth. √2 × orbital velocity. Remember: orbit ≈ 8 km/s, escape ≈ 11 km/s.

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.