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The knot (/ n ɒ t /) 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] [2] The ISO standard symbol for the knot is kn. [3]
Speed; system unit code (alternative) symbol or abbrev. notes sample default conversion combinations SI: metre per second: m/s m/s US spelling: meter per second 1.0 m/s (3.3 ft/s)
For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200 000 km/s (124 000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.
The metre per second is the unit of both speed (a scalar quantity) and velocity (a vector quantity, which has direction and magnitude) in the International System of Units (SI), equal to the speed of a body covering a distance of one metre in a time of one second.
kilometres per hour (symbol km/h); miles per hour (symbol mi/h or mph); knots (nautical miles per hour, symbol kn or kt); feet per second (symbol fps or ft/s); Mach number (dimensionless), speed divided by the speed of sound; in natural units (dimensionless), speed divided by the speed of light in vacuum (symbol c = 299 792 458 m/s).
SI, and hence the use of "km/h" (or "km h −1 " or "km·h −1 ") has now been adopted around the world in many areas related to health and safety [36] and in metrology [37] in addition to the SI unit metres per second ("m/s", "m s −1 " or "m·s −1 "). SI is also the preferred system of measure in academia and in education.
Other vehicles have digital speedometers which can be set to read out speeds in either MPH or km/h. Another common unit of speed is meters per second (m/s), used especially for lifts and cable cars. Odometers are permitted to record miles or kilometers, but must be clearly labeled as to which unit they record. Vehicle capacity sticker
The speed of sound in seawater depends on pressure (hence depth), temperature (a change of 1 °C ~ 4 m/s), and salinity (a change of 1‰ ~ 1 m/s), and empirical equations have been derived to accurately calculate the speed of sound from these variables. [25] [26] Other factors affecting the speed of sound are minor. Since in most ocean regions ...