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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. 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 ...

  4. Mach number - Wikipedia

    en.wikipedia.org/wiki/Mach_number

    The subsonic speed range is that range of speeds within which, all of the airflow over an aircraft is less than Mach 1. The critical Mach number (Mcrit) is lowest free stream Mach number at which airflow over any part of the aircraft first reaches Mach 1. So the subsonic speed range includes all speeds that are less than Mcrit. Transonic: 0.8–1.2

  5. 30 km/h zone - Wikipedia

    en.wikipedia.org/wiki/30_km/h_zone

    The road sign for a 30 km/h zone in Austria The road sign for a 20 mph zone in the UK. 30 km/h zones (30 kilometres per hour zones) and the similar 20 mph zones (20 miles per hour zones) are forms of speed management used across areas of urban roads in some jurisdictions. The nominal maximum speed limits in these zones are 30 kilometres per ...

  6. Speed - Wikipedia

    en.wikipedia.org/wiki/Speed

    For example, if a distance of 80 kilometres is driven in 1 hour, the average speed is 80 kilometres per hour. Likewise, if 320 kilometres are travelled in 4 hours, the average speed is also 80 kilometres per hour. When a distance in kilometres (km) is divided by a time in hours (h), the result is in kilometres per hour (km/h).

  7. Gravitational acceleration - Wikipedia

    en.wikipedia.org/wiki/Gravitational_acceleration

    Using the integral form of Gauss's Law, this formula can be extended to any pair of objects of which one is far more massive than the other — like a planet relative to any man-scale artifact. The distances between planets and between the planets and the Sun are (by many orders of magnitude) larger than the sizes of the sun and the planets.

  8. Rules of the Road: 25 mph is too fast. Is there a lower speed ...

    www.aol.com/rules-road-25-mph-too-030000807.html

    The maximum speed for the Saturn V rocket was 25,000 mph. The maximum speed of a Bugatti Chiron (the fastest production road car) is 305 mph. The Mitubishi Mirage (the cheapest car available in ...

  9. 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.