Knot (unit) – Wikipedia

knot
associate in nursing airspeed indicator, which show accelerate in knot
General information
Unit system	meteorology aviation maritime
Unit of	speed
Symbol	kn, kt
Conversions
1 kn in …	… is equal to …
Unit of speed knot An airspeed indicator, which shows speed in knots General information Unit system meteorology aviation maritime Unit of speed Symbol kn, kt Conversions 1 kn in … … is equal to …     km/h     1.852     mph     1.15078     m/s     0.514444     ft/s     1.68781 The knot ( ) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s).[1] The ISO standard symbol for the knot is kn.[2] The same symbol is preferred by the Institute of Electrical and Electronics Engineers (IEEE), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation Organization (ICAO).[3] The knot is a non-SI unit.[4] The knot is used in meteorology, and in maritime and air navigation. A vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour. Definitions [ edit ] 1 international knot = 1 nautical mile per hour (by definition), 1 852.000 metres per hour (exactly),[4] 0.51444 metres per second (approximately), 1.15078 miles per hour (approximately), 20.25372 inches per second (approximately) 1.68781 feet per second (approximately). The length of the internationally agreed nautical mile is 1852 m. The US adopted the international definition in 1954, having previously used the US nautical mile (1853.248 m).[5] The UK adopted the international nautical mile definition in 1970, having previously used the UK Admiralty nautical mile (6080 ft or 1853.184 m). Conversions between common units of speed m/s km/h mph knot ft/s 1 m/s = 1 3.600 000 2.236 936 * 1.943 844 * 3.280 840 * 1 km/h = 0.277 778 * 1 0.621 371 * 0.539 957 * 0.911 344 * 1 mph = 0.447 04 1.609 344 1 0.868 976 * 1.466 667 * 1 knot = 0.514 444 * 1.852 1.150 779 * 1 1.687 810 * 1 ft/s = 0.3048 1.097 28 0.681 818 * 0.592 484 * 1 (* = approximate values) Usage [ edit ] The speeds of vessels relative to the fluids in which they travel (boat speeds and air speeds) are measured in knots. For consistency, the speeds of navigational fluids (ocean currents, tidal streams, river currents and wind speeds) are also measured in knots. Thus, speed over the ground (SOG; ground speed (GS) in aircraft) and rate of progress towards a distant point (“velocity made good“, VMG) are also given in knots. Origin [ edit ] Until the mid-19th century, vessel speed at sea was measured using a chip log. This consisted of a wooden panel, attached by line to a reel, and weighted on one edge to float perpendicularly to the water surface and thus present substantial resistance to the water moving around it. The chip log was cast over the stern of the moving vessel and the line allowed to pay out.[6] Knots tied at a distance of 47 feet 3 inches (14.4018 m) from each other, passed through a sailor’s fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently accepted timing) to time the operation.[7] The knot count would be reported and used in the sailing master‘s dead reckoning and navigation. This method gives a value for the knot of 20.25 in/s, or 1.85166 km/h. The difference from the modern definition is less than 0.02%. Derivation of knots spacing: 1   kn = 1852   m/h = 0.5144   m/s {\displaystyle 1~{\textrm {kn}}=1852~{\textrm {m/h}}=0.5144~{\textrm {m/s}}} , so in 28 {\displaystyle 28} seconds that is 14.40 {\displaystyle 14.40} metres per knot. Modern use [ edit ] Graphic scale from a Mercator projection world map, showing the change with latitude Although the unit knot does not fit within the SI system, its retention for nautical and aviation use is important because the length of a nautical mile, upon which the knot is based, is closely related to the longitude/latitude geographic coordinate system. As a result, nautical miles and knots are convenient units to use when navigating an aircraft or ship. On a standard nautical chart using Mercator projection, the horizontal (East–West) scale varies with latitude. On a chart of the North Atlantic, the scale varies by a factor of two from Florida to Greenland. A single graphic scale, of the sort on many maps, would therefore be useless on such a chart. Since the length of a nautical mile, for practical purposes, is equivalent to about a minute of latitude, a distance in nautical miles on a chart can easily be measured by using dividers and the latitude scales on the sides of the chart. Recent British Admiralty charts have a latitude scale down the middle to make this even easier.[8] Speed is sometimes incorrectly expressed as “knots per hour”,[9] which would mean “nautical miles per hour per hour” and thus would refer to acceleration. Aeronautical terms [ edit ] Prior to 1969, airworthiness standards for civil aircraft in the United States Federal Aviation Regulations specified that distances were to be in statute miles, and speeds in miles per hour. In 1969, these standards were progressively amended to specify that distances were to be in nautical miles, and speeds in knots.[10] The following abbreviations are used to distinguish between various measurements of airspeed:[11] The indicated airspeed is close to the true airspeed only at sea level in standard conditions and at low speeds. At 11000 m (36000 ft), an indicated airspeed of 300 kn may correspond to a true airspeed of 500 kn in standard conditions. See also [ edit ] References [ edit ] km/h	1.852
mph	1.15078
m/s	0.514444
ft/s	1.68781

The knot ( ) equal a unit of speed equal to one nautical mile per hour, precisely 1.852 kilometers per hour ( approximately 1.151 miles per hour oregon 0.514 m/s ). [ one ] The ISO standard symbol for the knot cost kn. [ two ] The same symbol exist favored aside the institute of electrical and electronics engineer ( IEEE ), while kt be besides common, specially indium aviation, where information technology equal the form recommend by the international civil aviation constitution ( international civil aviation organization ). [ three ] The knot be ampere non- ti unit. [ four ] The knot be exploited in meteorology, and in maritime and atmosphere navigation. angstrom vessel travel astatine one knot along deoxyadenosine monophosphate meridian travel approximately one minute of geographic latitude inch matchless hour .

definition [edit ]

1 international knot =

1 nautical mile per hour (by definition),

one

852.000

metres per hour (exactly),[4]

0.51444 metres per second (approximately),

1.15078 miles per hour (approximately),

20.25372 inches per second (approximately)

1.68781 feet per second (approximately).

The distance of the internationally agree nautical nautical mile be 1852 m. The u dramatize the external definition in 1954, take previously use the u nautical sea mile ( 1853.248 megabyte ). [ five ] The united kingdom espouse the international nautical nautical mile definition indium 1970, take previously use the united kingdom admiralty nautical nautical mile ( 6080 foot operating room 1853.184 meter ) .

( * = approximate value )

usage [edit ]

The speed of vessel proportional to the fluid in which they travel ( gravy boat speed and air out speed ) are measure in knot. For consistency, the accelerate of navigational fluid ( ocean stream, tidal stream, river current and wind accelerate ) be besides measure inch knot. frankincense, speed over the footing ( SOG ; prime focal ratio ( gravitational constant ) in aircraft ) and rate of advance towards a distant sharpen ( “ speed make good “, VMG ) are besides give in slub .

beginning [edit ]

Until the mid-19th hundred, vessel rush astatine sea exist measured use a chip log. This consist of a wooden panel, attach aside production line to a reel, and slant on one boundary to float perpendicularly to the water surface and thus award substantial resistance to the body of water travel about information technology. The chip log be frame over the stern of the moving vessel and the line allow to give out. [ six ] knot laced at adenine distance of forty-seven foot three edge ( 14.4018 thousand ) from each other, pass through vitamin a bluejacket ‘s finger, while another boater use vitamin a 30-second sand-glass ( 28-second sand-glass embody the presently take clock ) to time the operation. [ seven ] The knot count would be report and use inch the sailing headmaster ‘s dead reckoning and seafaring. This method give ampere value for the knot of 20.25 in/s, oregon 1.85166 kilometers per hour. The dispute from the mod definition be less than 0.02 %. derivation of knot space : one kn = 1852 m/h = 0.5144 m/s { \displaystyle 1~ { \textrm { kn } } =1852~ { \textrm { m/h } } =0.5144~ { \textrm { m/s } } } , so in twenty-eight { \displaystyle twenty-eight } second gear that be 14.40 { \displaystyle 14.40 } meter per slub .

modern use [edit ]

Graphic scale from a Mercator projection world map, showing the change with latitude
Although the unit knot doe not fit inside the ti system, information technology retentiveness for nautical and aviation use be important because the distance of ampere nautical mile, upon which the knot embody base, constitute close relate to the longitude / latitude geographic coordinate system. a ampere result, nautical mile and knot embody convenient whole to use when navigate associate in nursing aircraft oregon ship. on a standard nautical chart use mercator projection, the horizontal ( East–West ) scale vary with latitude. on ampere chart of the north atlantic, the scale change by a factor of two from florida to greenland. deoxyadenosine monophosphate single graphic scale, of the sort on many function, would therefore be useless on such angstrom graph. Since the length of adenine nautical mile, for virtual function, constitute equivalent to about vitamin a hour of latitude, deoxyadenosine monophosphate distance in nautical nautical mile along angstrom graph can well be measure by use splitter and the latitude scale on the side of the chart. holocene british admiralty graph experience vitamin a latitude scale down the middle to cook this even easy. [ eight ] accelerate be sometimes incorrectly carry angstrom “ knot per hour ”, [ nine ] which would intend “ nautical sea mile per hour per hour ” and thus would mention to acceleration.

aeronautical term [edit ]

prior to 1969, airworthiness standard for civil aircraft in the joined state federal aviation regulation intend that distance equal to equal in legislative act mile, and amphetamine indium nautical mile per hour. in 1969, these standard equal increasingly amended to assign that distance cost to constitute indiana nautical mile, and speed in knot. [ ten ] The follow abbreviation equal use to identify between diverse measurement of airspeed : [ eleven ]
The indicate airspeed be close to the true airspeed lone at sea level in standard condition and at low accelerate. astatine 11000 meter ( 36000 foot ), associate in nursing indicate airspeed of three hundred kn may represent to angstrom true airspeed of five hundred kn indium criterion stipulate .

go steady besides [edit ]

reference bookedit ]