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  2. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    In 1709, the Reverend William Derham, Rector of Upminster, published a more accurate measure of the speed of sound, at 1,072 Parisian feet per second. [5] The Parisian foot was 325 mm . This is longer than the standard "international foot" in common use today, which was officially defined in 1959 as 304.8 mm , making the speed of sound at 20 ...

  3. English Engineering Units - Wikipedia

    en.wikipedia.org/wiki/English_Engineering_Units

    Units for other physical quantities are derived from this set as needed. In English Engineering Units, the pound-mass and the pound-force are distinct base units, and Newton's Second Law of Motion takes the form = where is the acceleration in ft/s 2 and g c = 32.174 lb·ft/(lbf·s 2).

  4. Knot (unit) - Wikipedia

    en.wikipedia.org/wiki/Knot_(unit)

    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 1 852 m. The US adopted the international definition in 1954, having previously used the US nautical mile (1 853.248 m). [6] The UK adopted the international ...

  5. Conversion of units - Wikipedia

    en.wikipedia.org/wiki/Conversion_of_units

    For example, 10 miles per hour can be converted to metres per second by using a sequence of conversion factors as shown below: = . Each conversion factor is chosen based on the relationship between one of the original units and one of the desired units (or some intermediary unit), before being rearranged to create a factor that cancels out the ...

  6. Foot per second - Wikipedia

    en.wikipedia.org/wiki/Foot_per_second

    The foot per second (plural feet per second) is a unit of both speed (scalar) and velocity (vector quantity, which includes direction). [1] It expresses the distance in feet (ft) traveled or displaced, divided by the time in seconds (s). [2] The corresponding unit in the International System of Units (SI) is the meter per second.

  7. List of unusual units of measurement - Wikipedia

    en.wikipedia.org/wiki/List_of_unusual_units_of...

    The term "second" comes from "the second minute division of an hour", as it is 1 ⁄ 60 of a minute, or 1 ⁄ 60 of 1 ⁄ 60 of an hour. While usually sub-second units are represented with SI prefixes on the second (e.g. milliseconds), this system can be extrapolated further, such that a "Third" would mean 1 ⁄ 60 of a second (16.7 ...

  8. Muzzle velocity - Wikipedia

    en.wikipedia.org/wiki/Muzzle_velocity

    FPS (feet per second) and MPH (miles per hour) are the most common American measurements for bullets. Several factors, including the type of firearm, the cartridge, and the barrel length, determine the bullet's muzzle velocity.

  9. Mach number - Wikipedia

    en.wikipedia.org/wiki/Mach_number

    If the speed of sound is not known, Mach number may be determined by measuring the various air pressures (static and dynamic) and using the following formula that is derived from Bernoulli's equation for Mach numbers less than 1.0. Assuming air to be an ideal gas, the formula to compute Mach number in a subsonic compressible flow is: [8]