Convert Cosmic Velocity - First (v₁) to Knot (UK) (kt (UK)) instantly.
About these units
Cosmic Velocity - First (v₁)
The first cosmic velocity is the minimum horizontal speed an object must achieve to enter a stable orbit around a planetary body without additional propulsion. For Earth, this value is about 7.9 km/s. At this speed, an object's forward motion precisely balances with the gravitational pull downward, creating continuous free-fall—the essence of orbital motion. This velocity is foundational in orbital mechanics. Spacecraft reaching Low Earth Orbit (LEO) must achieve at least this horizontal speed, even if their vertical ascent profile varies. Understanding v₁ was essential in the early space age: it represented the threshold between atmospheric flight and true spaceflight, marking human entry into the orbital era.
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 Modern UK practice fully aligns with the international knot (1 nautical mile per hour), but historical documents and charts may reference older UK knot values.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.