Definition:Knot (Unit of Measurement)
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This page is about knot in the context of units of measurement. For other uses, see knot.
Definition
The knot is a unit of speed which is used for air and sea navigation.
It is defined as $1$ nautical mile per hour.
It is now defined as exactly $1 \, 852$ metres per hour.
Conversion Factors
| \(\ds \) | \(\) | \(\ds 1\) | knot | |||||||||||
| \(\ds \) | \(=\) | \(\ds 1 \, 852\) | metres per hour | \(\quad\) (exact) | ||||||||||
| \(\ds \) | \(=\) | \(\ds 1 \cdotp 852\) | kilometres per hour | \(\quad\) (exact) | ||||||||||
| \(\ds \) | \(\approx\) | \(\ds 1 \cdotp 68781 \, 0\) | feet per second | |||||||||||
| \(\ds \) | \(\approx\) | \(\ds 0 \cdotp 51444 \, 4\) | metres per second | |||||||||||
| \(\ds \) | \(\approx\) | \(\ds 1 \cdotp 15077 \, 9\) | (international) miles per hour |
Also see
Historical Note
The knot is defined in terms of the nautical mile, that is, $1852$ metres or approximately $6076$ feet.
However, the admiralty mile, that is, $6080$ feet, has until fairly recently also been used to define the knot.
Because of this confusion, it is recommended that the knot is determined to ne unsuitable for accurate measurements.
Sources
- 1969: J.C. Anderson, D.M. Hum, B.G. Neal and J.H. Whitelaw: Data and Formulae for Engineering Students (2nd ed.) ... (previous) ... (next): $2.$ Unit Conversion Factors
- 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text I$. Spherical Trigonometry: Exercise $4$.
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): knot: 2.
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): knot: 2.
- 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): knot