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  2. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.

  3. Foot per second - Wikipedia

    en.wikipedia.org/wiki/Foot_per_second

    km/h. 1.0973. 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.

  4. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    Special relativity. The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).

  5. Wind speed - Wikipedia

    en.wikipedia.org/wiki/Wind_speed

    In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed affects weather forecasting, aviation and maritime operations, construction projects, growth and ...

  6. Knot (unit) - Wikipedia

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

    The knot (/ nɒt /) 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] 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 ...

  7. Subsonic ammunition - Wikipedia

    en.wikipedia.org/wiki/Subsonic_ammunition

    In this instance, heavier bullets are loaded in standard ammunition, which reduces muzzle velocity below the speed of sound. As an example, the very common 9×19mm Parabellum standard military round is a 7.5 grams (116 gr) bullet at velocities typically around 360 metres per second (1,200 ft/s).

  8. Nautical mile - Wikipedia

    en.wikipedia.org/wiki/Nautical_mile

    A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. [2] [3] [4] Historically, it was defined as the meridian arc length corresponding to one minute (⁠ 1 / 60 ⁠ of a degree) of latitude at the equator, so that Earth's polar circumference is very near to 21,600 nautical miles (that is 60 minutes × 360 degrees).

  9. Muzzle velocity - Wikipedia

    en.wikipedia.org/wiki/Muzzle_velocity

    Muzzle velocity. Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball / shots or shell) with respect to [1] the muzzle at the moment it leaves the end of a gun 's barrel (i.e. the muzzle). [2] Firearm muzzle velocities range from approximately 120 m/s (390 ft/s) to 370 m/s (1,200 ft/s) in black powder muskets, [3] to more ...