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  2. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    T 25 is 298.15 K (= 25 °C = 77 °F), giving a value of 346.1 m/s (= 1 135.6 ft/s = 1246 km/h = 774.3 mph = 672.8 kn). In fact, assuming an ideal gas , the speed of sound c depends on temperature and composition only, not on the pressure or density (since these change in lockstep for a given temperature and cancel out).

  3. Speed limits in the United States - Wikipedia

    en.wikipedia.org/wiki/Speed_limits_in_the_United...

    Prior to 2009, a speed limit could be defined in kilometers per hour (km/h) as well as miles per hour (mph). The 2003 version of the MUTCD stated that "speed limits shown shall be in multiples of 10 km/h or 5 mph." [118] If a speed limit sign indicated km/h, the number was circumscribed and "km/h" was written below. Prior to 2003, metric speed ...

  4. Miles per hour - Wikipedia

    en.wikipedia.org/wiki/Miles_per_hour

    Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom , the United States , and a number of smaller countries, most of which are UK or US territories, or have close historical ties with the UK or US.

  5. Beaufort scale - Wikipedia

    en.wikipedia.org/wiki/Beaufort_scale

    < 1 mph < 1 km/h 0–0.2 m/s: 0 ft 0 m Sea like a mirror Smoke rises vertically 1 Light air 1–3 knots 1–3 mph 1–5 km/h 0.3–1.5 m/s 0–1 ft 0–0.3 m Ripples with appearance of scales are formed, without foam crests Direction shown by smoke drift but not by wind vanes 2 Light breeze 4–6 knots 4–7 mph 6–11 km/h 1.6–3.3 m/s

  6. Kilometres per hour - Wikipedia

    en.wikipedia.org/wiki/Kilometres_per_hour

    Abbreviations for "kilometres per hour" did not appear in the English language until the late nineteenth century. The kilometre, a unit of length, first appeared in English in 1810, [9] and the compound unit of speed "kilometers per hour" was in use in the US by 1866. [10] "Kilometres per hour" did not begin to be abbreviated in print until ...

  7. Knot (unit) - Wikipedia

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

    A single graphic scale, of the sort on many maps, would therefore be useless on such a chart. Since the length of a nautical mile, for practical purposes, is equivalent to about a minute of latitude, a distance in nautical miles on a chart can easily be measured by using dividers and the latitude scales on the sides of the chart.

  8. Tropical cyclone intensity scales - Wikipedia

    en.wikipedia.org/wiki/Tropical_cyclone_intensity...

    A Category 4 hurricane has winds of 113 to 136 kn (130 to 157 mph; 209 to 252 km/h), while a Category 5 hurricane has winds of at least 137 kn (158 mph; 254 km/h). [ 1 ] [ 3 ] A post tropical cyclone is a system that has weakened, into a remnant low or has dissipated and formal advisories are usually discontinued at this stage. [ 1 ]

  9. Speed limits in the United States by jurisdiction - Wikipedia

    en.wikipedia.org/wiki/Speed_limits_in_the_United...

    15 mph (24 km/h) in a school zone within 30 minutes of the beginning or end of the school day or whenever/wherever children are present; 20 mph (32 km/h) near an intersection "when the operator's view is obstructed", unless right-of-way is given via signage; 25 mph (40 km/h) in business or residential districts, or other built-up areas