Sea speed in knots and km/h. What is a nautical mile and what is a nautical knot equal to? What is the relationship between nautical mile and knot

One sea knot is equal to one thousand eight hundred fifty-two meters or one kilometer eight hundred fifty-two meters

By international definition, one knot is equal to 1.852 km/h (exact) or 0.5144444 m/s. This unit of measurement, although non-systemic, is allowed for use along with SI units.

A knot is a linear speed of 1 nautical mile per hour.

one sea knot is equal to 1852 meters => 1 km 852 m

The origin of the name is related to the principle of using sector lag. The speed of the vessel was determined as the number of knots on the line (thin cable) that passed through the hand of the measurer in a certain time (usually 15 seconds).

Knots do not measure distance but speed, number of knots = number of nautical miles per hour, nautical mile = 1.8 km.

The hub and international nautical mile are widely used in maritime and air transport. Knots were considered the most common measurement in England until 1965, but after a re-decision they became known as miles.

Initially, this value corresponded to the length of 1/60 degree of the arc of a circle on the surface of the Earth with the center coinciding with the center of the planet. In other words, if we consider any meridian, then a nautical mile will be approximately equal to the length of one minute of latitude. Since the shape of the Earth is somewhat different from the outline of a perfect sphere, the length of 1 minute of degree of the meridian in question may differ slightly depending on latitude. This distance is greatest at the poles - 1861.6 m, and least at the equator - 1842.9 m. To avoid confusion, it was proposed to unify the length of the nautical mile. The length taken as a basis was 1 minute of degree at 45º latitude (1852.2 m). This definition led to the fact that the nautical mile became convenient for calculating navigation problems. For example, if you need to measure a distance of 20 miles on a map, then it will be enough to measure 20 arc minutes with a compass on any meridian marked on the map.

1 sea knot is equal to:

  • kilometer per second (km/s) 0.0005144
  • meter per second (m/s) 0.5144
  • kilometer per hour (km/h) 1.852
  • meter per minute 30.87

You can find out the speed from 0 to 100 nautical knots converted into km/h and m/sec in this table:

Speed ​​in knots Speed ​​in km/h Speed ​​in m/sec
1 1.852 km/h 0.514 m/s
2 3.704 km/h 1.028 m/s
3 5.556 km/h 1.542 m/s
4 7.408 km/h 2.056 m/s
5 9.26 km/h 2.57 m/sec
6 11.112 km/h 3.084 m/s
7 12.964 km/h 3.598 m/s
8 14.816 km/h 4.112 m/s
9 16.668 km/h 4.626 m/s
10 18.52 km/h 5.14 m/sec
11 20.372 km/h 5.654 m/s
12 22.224 km/h 6.168 m/s
13 24.076 km/h 6.682 m/s
14 25.928 km/h 7.196 m/s
15 27.78 km/h 7.71 m/sec
16 29.632 km/h 8.224 m/s
17 31.484 km/h 8.738 m/s
18 33.336 km/h 9.252 m/s
19 35.188 km/h 9.766 m/s
20 37.04 km/h 10.28 m/sec
21 38.892 km/h 10.794 m/s
22 40.744 km/h 11.308 m/s
23 42.596 km/h 11.822 m/s
24 44.448 km/h 12.336 m/s
25 46.3 km/h 12.85 m/sec
26 48.152 km/h 13.364 m/s
27 50.004 km/h 13.878 m/s
28 51.856 km/h 14.392 m/s
29 53.708 km/h 14.906 m/s
30 55.56 km/h 15.42 m/sec
31 57.412 km/h 15.934 m/s
32 59.264 km/h 16.448 m/s
33 61.116 km/h 16.962 m/s
34 62.968 km/h 17.476 m/s
35 64.82 km/h 17.99 m/sec
36 66.672 km/h 18.504 m/s
37 68.524 km/h 19.018 m/s
38 70.376 km/h 19.532 m/s
39 72.228 km/h 20.046 m/s
40 74.08 km/h 20.56 m/sec
41 75.932 km/h 21.074 m/s
42 77.784 km/h 21.588 m/s
43 79.636 km/h 22.102 m/s
44 81.488 km/h 22.616 m/s
45 83.34 km/h 23.13 m/sec
46 85.192 km/h 23.644 m/s
47 87.044 km/h 24.158 m/s
48 88.896 km/h 24.672 m/s
49 90.748 km/h 25.186 m/s
50 92.6 km/h 25.7 m/sec
51 94.452 km/h 26.214 m/s
52 96.304 km/h 26.728 m/s
53 98.156 km/h 27.242 m/s
54 100.008 km/h 27.756 m/s
55 101.86 km/h 28.27 m/sec
56 103.712 km/h 28.784 m/s
57 105.564 km/h 29.298 m/s
58 107.416 km/h 29.812 m/s
59 109.268 km/h 30.326 m/s
60 111.12 km/h 30.84 m/sec
61 112.972 km/h 31.354 m/s
62 114.824 km/h 31.868 m/s
63 116.676 km/h 32.382 m/s
64 118.528 km/h 32.896 m/s
65 120.38 km/h 33.41 m/sec
66 122.232 km/h 33.924 m/s
67 124.084 km/h 34.438 m/s
68 125.936 km/h 34.952 m/s
69 127.788 km/h 35.466 m/s
70 129.64 km/h 35.98 m/sec
71 131.492 km/h 36.494 m/s
72 133.344 km/h 37.008 m/s
73 135.196 km/h 37.522 m/s
74 137.048 km/h 38.036 m/s
75 138.9 km/h 38.55 m/sec
76 140.752 km/h 39.064 m/s
77 142.604 km/h 39.578 m/s
78 144.456 km/h 40.092 m/s
79 146.308 km/h 40.606 m/s
80 148.16 km/h 41.12 m/sec
81 150.012 km/h 41.634 m/s
82 151.864 km/h 42.148 m/s
83 153.716 km/h 42.662 m/s
84 155.568 km/h 43.176 m/s
85 157.42 km/h 43.69 m/sec
86 159.272 km/h 44.204 m/s
87 161.124 km/h 44.718 m/s
88 162.976 km/h 45.232 m/s
89 164.828 km/h 45.746 m/s
90 166.68 km/h 46.26 m/sec
91 168.532 km/h 46.774 m/s
92 170.384 km/h 47.288 m/s
93 172.236 km/h 47.802 m/s
94 174.088 km/h 48.316 m/s
95 175.94 km/h 48.83 m/sec
96 177.792 km/h 49.344 m/s
97 179.644 km/h 49.858 m/s
98 181.496 km/h 50.372 m/s
99 183.348 km/h 50.886 m/s
100 185.2 km/h 51.4 m/sec
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Used in maritime and aviation practice.

By international definition, one knot is equal to 1.852 km/h (1 nautical mile per hour) or 0.514 m/s. This unit of measurement, although non-systemic, is allowed for use along with units of the International System of Units (SI). In the Russian Federation, the node is approved for use as an off-system unit without a time limit with the scope of application “maritime navigation”.

The prevalence of the knot as a unit of measurement is associated with the significant convenience of its use in navigation calculations: a ship moving at a speed of 1 knot along the meridian passes one arc minute of geographic latitude in one hour.

The origin of the name is related to the principle of using sector lag. The speed of the vessel was determined as the number of knots on the line (thin cable) that passed through the hand of the measurer in a certain time (usually 15 seconds or 1 minute). In this case, the distance between adjacent nodes on the line and the measurement time were selected in such a way that this amount was numerically equal to the speed of the vessel, expressed in nautical miles per hour. A knot is an independent unit of speed. To say: “The ship is sailing at a speed of 36 knots per hour” is incorrect. The absurdity of such an expression is very well described in the story of L.S. 

Sobolev “The Flying Dutchman”, an excerpt from which is given below.

Tell me, captain, what is our speed? - Raising his glasses from his notebook, the guest asked again.

Guzhevoy already opened his mouth to answer with his usual wit that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:

Allowed: full speed, twelve knots.

The lag cable, released while moving from the stern, broke into knots at a distance of 1/120 of a mile (50 feet). By counting the number of knots that travel in half a minute (1/120 of an hour), you can find out the speed in nautical miles per hour. It follows that the expression “30 knots per hour” is clearly meaningless: it turns out that the ship, instead of a decent speed of 56 km/h, drags 1500 feet (~460 m) per hour, which is incorrect.

Knots and miles per hour should not be confused. A knot is one nautical (or nautical) mile (1852 meters) per hour, and "mile per hour" (mph, miles pro hour), widely used in Great Britain and North America, is a statute mile (1609 meters) in hour.

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    You may have heard something like: “the speed of a certain aircraft is Mach 2.” There are speed records on earth that allow us to talk about speed in terms of Mach number.

Sometimes the notation is also used kt) - unit of speed. Equal to the speed of uniform motion at which a body travels a distance of one nautical mile in one hour. It is used in maritime and aviation practice, in meteorology, and is the basic unit of speed in navigation.

According to international definition, one knot is equal to 1852 m/h exactly or 0.51444... m/s. This unit of measurement, although non-systemic, is allowed for use along with units of the International System of Units (SI). In the Russian Federation, the unit is approved for use as an off-system unit without a time limit with the scope of application “marine navigation”. The unit is included in the All-Russian Classifier of Units of Measurement.

The prevalence of the knot as a unit of measurement is associated with the significant convenience of its use in navigation calculations: a ship moving at a speed of 1 knot along the meridian passes one arc minute of geographic latitude in one hour.

The origin of the name is related to the principle of using a manual sector log, which in its simplest form was a plank tied to a long thin cable (lagline) in such a way that when thrown overboard of a moving vessel, it would be braked by the water. Knots were tied on the laglin at equal distances from each other; the distance was selected such that the number of knots on the lagline being etched overboard, escaping from the lag view and passing through the measuring hand in a certain time, was numerically equal to the speed of the vessel, expressed in nautical miles per hour.

A knot is an independent unit of speed. To say: “The ship is moving at a speed of 36 knots per hour” is incorrect. The fallacy of such an expression is illustrated in the story “The Flying Dutchman” by L. S. Sobolev, an excerpt from which is given below:

Sobolev “The Flying Dutchman”, an excerpt from which is given below.

Guzhevoy already opened his mouth to answer with his usual wit, that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:

Guzhevoy already opened his mouth to answer with his usual wit that there were six knots per hour - in the first, and in the second they didn’t pull even three, but Piychik warned him:

- Leonid Sergeevich Sobolev. Stories of Captain 2nd Rank V. L. Kirdyaga, heard from him during the “Great Seat”

Knot and nautical mile are widely used in maritime and air transport. The knot is the only widely used unit of speed that has its own name. Decimal prefixes (kilo-, milli-, etc.), which are used to form multiples and submultiples, are not used with the “knot” unit.

Knots and miles per hour should not be confused. A knot is one nautical (or nautical) mile (1852 meters) per hour, and "mile per hour" (English mph, miles per hour), widely used in Great Britain and North America, is a statute mile (1609 meters) in hour.

Before the introduction of the international knot, similar knot definitions were also used, based on different definitions of the nautical mile. In the USA, until 1952, a knot based on the American nautical mile (1852.249 m) was used. In Great Britain until 1970 (as well as in the countries of the British Commonwealth), a unit based on the British or Admiralty nautical mile (1852.184 m) was used. The difference between both definitions and the modern definition of a node is about 0.01% and is insignificant in almost all practical cases.

There is a simple mnemonic for quickly mentally converting knots to kilometers per hour: “multiply by two and subtract 10 percent.” For example, speed 15 knots, 15×2 = 30 km/h, subtract 10% = 3 km/h, we get 27 km/h. The rule gives values ​​with an error of less than 3%. To recalculate km/h → nodes, the reverse algorithm is used: the speed in km/h is divided by 2 and 10% is added to the resulting value. For example, 20 km/h → 10 knots → 11 knots(the exact value is 10.799136... nodes).

Notes

  1. Regulations on units of quantities allowed for use in the Russian Federation. Approved by Decree of the Government of the Russian Federation No. 879 of October 31, 2009.
  2. The international designation “kn” (from the English “knot”) is established by the ISO 80000-3 standard.
  3. Not recommended because it is the same as the international designation for kiloton.
  4. Dengub V. M., Smirnov V. G. Units of quantities. Dictionary-reference book. - M.: Standards Publishing House, 1990. - P. 117. - 240 p. - ISBN 5-7050-0118-5.

Nautical mile - the average arc length of one minute of the earth's meridian.
Arc length of one minute of the earth's meridian 1" = 1852.23 - 9.34 cos 2φ,
where φ is the latitude of the vessel in degrees.
The length of a nautical mile adopted in Russia is 1852.00 meters. Approximately 6080 feet.
Why 1852? If we take the shape of the Earth as a sphere, then the circumference along the meridian will be 40,000,000 meters. Hence 40,000,000 m: 360° = 40,000,000: 360*60" = 40,000,000: 21,600" = 1851, 85 meters in 1".

Example: distance to port 48 miles.
Or: 43 miles 8 cables. Or: 43.8 miles.

Cable - one tenth of a nautical mile, rounded equal to 185 meters. 1 mile = 10 kbt.

Example:the distance to the ship is 14 cables.

Knot - one nautical mile per hour (1.852 km/h) or 0.514 m/s (meters per second).

Example:ship speed 23 knots.

Knot is a linear speed of 1 nautical mile per hour. The term “knot” appeared in the era of sailing, when the speed of a ship was measured using the so-called sector lag - a sector-shaped wooden shield released from the stern of the ship into the water on a lagline (braided rope). Such a sector was held by the extensions of the laglin at three points, due to which it maintained a perpendicular position in the water to the direction of the vessel's progress. Since the sector is slowed down by water, the lagline was etched approximately at the speed of the ship. If the laglin was divided into sections of 50.7 feet with the help of knots, that is, equal to 1\120 miles (6080\50.7 = 120), then at a speed of 1 knot the laglin will be etched in 1 minute or 1\60 hours by 1/60 miles (2 knots), and in 0.5 minutes - by 1 knot. If, for example, 9 knots were etched in 0.5 minutes, then it was considered that the ship was moving at a speed of 9 knots.
On English maps they are also used

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1 kilometer per hour [km/h] = 0.539956803455724 knot [kt]

Initial value

Converted value

meter per second meter per hour meter per minute kilometer per hour kilometer per minute kilometer per second centimeter per hour centimeter per minute centimeter per second millimeter per hour millimeter per minute millimeter per second foot per hour foot per minute foot per second yard per hour yard per minute yard per second mile per hour mile per minute miles per second knot knot (UK) speed of light in vacuum first cosmic speed second cosmic speed third cosmic speed speed of rotation of the Earth speed of sound in fresh water speed of sound in sea water (20°C, depth 10 meters) Mach number (20°C, 1 atm) Mach number (SI standard)

More about speed

General information

Speed ​​is a measure of the distance traveled in a certain time. Speed ​​can be a scalar quantity or a vector quantity - the direction of movement is taken into account. The speed of movement in a straight line is called linear, and in a circle - angular.

Speed ​​measurement

Average speed v found by dividing the total distance traveled ∆ x for total time ∆ t: v = ∆x/∆t.

In the SI system, speed is measured in meters per second. Kilometers per hour in the metric system and miles per hour in the US and UK are also widely used. When, in addition to the magnitude, the direction is also indicated, for example, 10 meters per second to the north, then we are talking about vector velocity.

The speed of bodies moving with acceleration can be found using the formulas:

  • a, with initial speed u during the period ∆ t, has a finite speed v = u + a×∆ t.
  • A body moving with constant acceleration a, with initial speed u and final speed v, has an average speed ∆ v = (u + v)/2.

Average speeds

Speed ​​of light and sound

According to the theory of relativity, the speed of light in a vacuum is the highest speed at which energy and information can travel. It is denoted by the constant c and is equal to c= 299,792,458 meters per second. Matter cannot move at the speed of light because it would require an infinite amount of energy, which is impossible.

The speed of sound is usually measured in an elastic medium, and is equal to 343.2 meters per second in dry air at a temperature of 20 °C. The speed of sound is lowest in gases and highest in solids. It depends on the density, elasticity, and shear modulus of the substance (which shows the degree of deformation of the substance under shear load). Mach number M is the ratio of the speed of a body in a liquid or gas medium to the speed of sound in this medium. It can be calculated using the formula:

M = v/a,

Where a is the speed of sound in the medium, and v- body speed. Mach number is commonly used in determining speeds close to the speed of sound, such as airplane speeds. This value is not constant; it depends on the state of the medium, which, in turn, depends on pressure and temperature. Supersonic speed is a speed exceeding Mach 1.

Vehicle speed

Below are some vehicle speeds.

  • Passenger aircraft with turbofan engines: The cruising speed of passenger aircraft is from 244 to 257 meters per second, which corresponds to 878–926 kilometers per hour or M = 0.83–0.87.
  • High-speed trains (like the Shinkansen in Japan): such trains reach maximum speeds of 36 to 122 meters per second, that is, from 130 to 440 kilometers per hour.

Animal speed

The maximum speeds of some animals are approximately equal to:

Human speed

  • People walk at speeds of about 1.4 meters per second, or 5 kilometers per hour, and run at speeds of up to about 8.3 meters per second, or 30 kilometers per hour.

Examples of different speeds

Four-dimensional speed

In classical mechanics, vector velocity is measured in three-dimensional space. According to the special theory of relativity, space is four-dimensional, and the measurement of speed also takes into account the fourth dimension - space-time. This speed is called four-dimensional speed. Its direction may change, but its magnitude is constant and equal to c, that is, the speed of light. Four-dimensional speed is defined as

U = ∂x/∂τ,

Where x represents a world line - a curve in space-time along which a body moves, and τ is the "proper time" equal to the interval along the world line.

Group speed

Group velocity is the speed of wave propagation, describing the speed of propagation of a group of waves and determining the speed of wave energy transfer. It can be calculated as ∂ ω /∂k, Where k is the wave number, and ω - angular frequency. K measured in radians/meter, and the scalar frequency of wave oscillation ω - in radians per second.

Hypersonic speed

Hypersonic speed is a speed exceeding 3000 meters per second, that is, many times faster than the speed of sound. Solid bodies moving at such speeds acquire the properties of liquids, since, thanks to inertia, the loads in this state are stronger than the forces that hold the molecules of a substance together during collisions with other bodies. At ultrahigh hypersonic speeds, two colliding solids turn into gas. In space, bodies move at exactly this speed, and engineers designing spacecraft, orbital stations and spacesuits must consider the possibility of a station or astronaut colliding with space debris and other objects when working in outer space. In such a collision, the skin of the spacecraft and the spacesuit suffer. Hardware developers conduct hypersonic collision experiments in special laboratories to determine how intense impacts the suits can withstand, as well as the skin and other parts of the spacecraft, such as fuel tanks and solar panels, testing their strength. To do this, spacesuits and skin are exposed to impacts from various objects from a special installation at supersonic speeds exceeding 7500 meters per second.

 

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