How many km / h is the unit of speed in navigation? Such as the title

How many km / h is the unit of speed in navigation? Such as the title

In the 16th century, a clever sailor threw a floating body with a rope to the surface of the water when the ship was moving forward. According to the length of the rope pulled out in a certain period of time, he calculated the speed of the ship. Because the quicksand timer was used at that time, in order to calculate the speed of the ship more accurately, the sailor made many equidistant knots on the rope, The whole speed counting rope is divided into many knots. As long as you calculate the knots of the rope released in a certain period of time, you can know the sailing speed of the ship. Since then, "knots" has become the international common unit of sailing speed
1 knot = 1 nautical mile / h 1 nautical mile = 1.825 km

Is Mach 1 a unit of speed? How many kilometers per hour

Mach, [Mach] the ratio of the speed of aircraft and rocket moving in the air to the speed of sound, that is, about 340 m / s, 1126 km / h, named after the Austrian physicist Ernst Mach, [Mach number] represents the ratio of the speed of an object to the speed of sound in the surrounding air

What is the speed unit of submarine's underwater speed, km / h?

In the past, the crew used to measure the ship's speed. Every time they walked 1 nautical mile, the crew would make a knot on the rope they put down. Later, the knot would be used as the unit of ship's speed
1 knot (KN) = 1 knots = (1852 / 3600) m / S is the unit of speed
The unit of length is n mile = 1852m
That's 1.852 kilometers per hour
The speed unit of land vehicles, air planes and river ships is usually km / h, while the speed unit of sea ships (including warships) is called "knots"
As early as the 16th century, navigation on the sea was quite developed, but at that time, there was no clock and no voyage recorder, so it was difficult to accurately determine the speed of a ship. However, a clever sailor came up with a clever method. He threw a floating body with a rope into the sea when the ship was sailing, and then calculated the ship's speed according to the length of the rope pulled out in a certain period of time, In order to calculate the ship's speed more accurately, sometimes the rope released is very long, so many knots are made at the same distance of the rope. In this way, the whole speed rope is divided into several sections. As long as the number of sections of the rope pulled in the same unit time is measured, the corresponding speed will be measured. Therefore, "section" becomes the unit of measurement of the ship's speed, The unit of measurement for velocity of sea water, wind speed at sea, torpedo and other underwater weapons is also commonly used internationally
The code of "section" is the prefix of "knot" in English, which is expressed by "kn". 1 section is equal to 1 nautical mile per hour, that is, 1.852 kilometers per hour. The unit of short distance measurement in navigation is "chain", 1 chain is equal to 1 / 10 nautical mile, and the code is the prefix of "cable", which is used as "cab"
The nautical mile is the unit of length of the sea. It originally refers to the length of one minute of latitude on the earth's meridian. Because the earth is slightly ellipsoidal, the radian of one minute varies slightly at different latitudes. On the equator, one nautical mile is about 1843 meters; at 45 ° latitude, it is about 1852.2 meters; at the two poles, it is about 1861.6 meters, In 1948, the International Conference on human life safety recognized that 1852 meters or 6o76.115 feet was 1 nautical mile, so 1852 meters was adopted as the standard nautical mile length internationally. China recognized this standard and used the code "m" to indicate it
In addition, the length unit of anchor chain segment manufacturing and use mark on ships also uses "section". Generally, the length of anchor chain is 27.5m as a section, and the use mark on Chinese ships is 20m as a section
The speedometer of modern seagoing ships has been very advanced, some of which can be displayed digitally at any time. The "throw rope and count knots" has long been a history, but "knots" is still used as the speed unit of seagoing ships