Convert Knot (UK) (kt (UK)) to Cosmic Velocity - Second (v₂) instantly.
About these units
Knot (UK) (kt (UK))
The UK knot historically varied slightly from the international knot because the UK used different values for the nautical mile depending on era and maritime authority. Though the differences were minor, they mattered in navigation, where precision affects charting, dead reckoning, and ocean voyaging. Modern UK practice fully aligns with the international knot (1 nautical mile per hour), but historical documents and charts may reference older UK knot values. The knot's rich maritime heritage—used by sailors measuring speed with knotted ropes dragged along the water—makes it one of the oldest continuously used speed units.
Cosmic Velocity - Second (v₂)
The second cosmic velocity is the escape velocity, the speed required to completely overcome a planet's gravitational attraction without further propulsion. For Earth, this speed is about 11.2 km/s. It is higher than v₁ because escaping gravity requires exceeding orbital balance entirely, not merely achieving stable free fall. Escape velocity underlies missions to the Moon, other planets, and deep space probes. Reaching v₂ allows spacecraft to travel along trajectories that leave Earth's gravitational well permanently unless acted on by external forces. This value symbolizes humanity's ability to break free from its home world—a critical milestone in exploration.