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| ==Etymology== | | ==Etymology== |
− | [http://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English] spede, from [http://nordan.daynal.org/wiki/index.php?title=English#ca._600-1100.09THE_OLD_ENGLISH.2C_OR_ANGLO-SAXON_PERIOD Old English] spēd; akin to Old High German spuot prosperity, speed, Old English spōwan to succeed, [[Latin]] spes [[hope]], Lithuanian spėti to be in [[time]] | + | [https://nordan.daynal.org/wiki/index.php?title=English#ca._1100-1500_.09THE_MIDDLE_ENGLISH_PERIOD Middle English] spede, from [https://nordan.daynal.org/wiki/index.php?title=English#ca._600-1100.09THE_OLD_ENGLISH.2C_OR_ANGLO-SAXON_PERIOD Old English] spēd; akin to Old High German spuot prosperity, speed, Old English spōwan to succeed, [[Latin]] spes [[hope]], Lithuanian spėti to be in [[time]] |
− | *Date: before [http://www.wikipedia.org/wiki/12th_Century 12th century] | + | *Date: before [https://www.wikipedia.org/wiki/12th_Century 12th century] |
| + | <center>For lessons on the related [[topic]] of '''''[[Acceleration]]''''', follow [https://nordan.daynal.org/wiki/index.php?title=Category:Acceleration '''''this link'''''].</center> |
| ==Definitions== | | ==Definitions== |
| + | [[File:Speed_of_light_from_Earth_to_Moon.gif|center|frame|<center>Speed of light from [[Earth]] to the Moon.</center>]] |
| *1 archaic : prosperity in an undertaking : success | | *1 archaic : prosperity in an undertaking : success |
| *2 a : the act or state of moving swiftly : swiftness b : rate of motion: as (1) : velocity 1 (2) : the magnitude of a velocity irrespective of direction c : impetus | | *2 a : the act or state of moving swiftly : swiftness b : rate of motion: as (1) : velocity 1 (2) : the magnitude of a velocity irrespective of direction c : impetus |
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| *7 : methamphetamine; also : a related stimulant drug and especially an amphetamine | | *7 : methamphetamine; also : a related stimulant drug and especially an amphetamine |
| ==Description== | | ==Description== |
− | In kinematics, the instantaneous [[speed]] of an object (denoted v) is the [[magnitude]] of its instantaneous [[velocity]] (the rate of [[change]] of its position); it is thus the [http://en.wikipedia.org/wiki/Scalar_(physics) scalar] [[equivalent]] of [[velocity]]. The [[average]] speed of an object in an [[interval]] of [[time]] is the distance [[traveled]] by the object divided by the duration of the interval; the instantaneous speed is the [[limit]] of the [[average]] speed as the duration of the time interval approaches zero . | + | In kinematics, the instantaneous [[speed]] of an object (denoted v) is the [[magnitude]] of its instantaneous [[velocity]] (the rate of [[change]] of its position); it is thus the [https://en.wikipedia.org/wiki/Scalar_(physics) scalar] [[equivalent]] of [[velocity]]. The [[average]] speed of an object in an [[interval]] of [[time]] is the distance [[traveled]] by the object divided by the duration of the interval; the instantaneous speed is the [[limit]] of the [[average]] speed as the duration of the time interval approaches zero . |
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− | Like [[velocity]], speed has the [[dimensions]] of a length divided by a [[time]]; the [http://en.wikipedia.org/wiki/International_System_of_Units SI unit] of speed is the [http://en.wikipedia.org/wiki/Meter_per_second meter per second], but the most usual [[unit]] of speed in everyday usage is the [http://en.wikipedia.org/wiki/Kilometer_per_hour kilometer per hour] or, in certain countries, the [http://en.wikipedia.org/wiki/Mile_per_hour mile per hour]. | + | Like [[velocity]], speed has the [[dimensions]] of a length divided by a [[time]]; the [https://en.wikipedia.org/wiki/International_System_of_Units SI unit] of speed is the [https://en.wikipedia.org/wiki/Meter_per_second meter per second], but the most usual [[unit]] of speed in everyday usage is the [https://en.wikipedia.org/wiki/Kilometer_per_hour kilometer per hour] or, in certain countries, the [https://en.wikipedia.org/wiki/Mile_per_hour mile per hour]. |
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− | The fastest possible speed at which [[energy]] or [[information]] can [[travel]], according to [http://en.wikipedia.org/wiki/Special_relativity special relativity], is the [[speed of light]] in vacuum c = 299,792,458 meters per second, approximately 1079 million kilometers (671 million miles) per hour. [[Matter]] cannot quite reach the [[speed of light]], as this would require an [[infinite]] amount of [[energy]].[http://en.wikipedia.org/wiki/Speed | + | The fastest possible speed at which [[energy]] or [[information]] can [[travel]], according to [https://en.wikipedia.org/wiki/Special_relativity special relativity], is the [[speed of light]] in vacuum c = 299,792,458 meters per second, approximately 1079 million kilometers (671 million miles) per hour. [[Matter]] cannot quite reach the [[speed of light]], as this would require an [[infinite]] amount of [[energy]].[https://en.wikipedia.org/wiki/Speed |
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| The instantaneous speed v is defined as the magnitude of the instantaneous [[velocity]] v, that is the derivative of the position r with respect to [[time]]: | | The instantaneous speed v is defined as the magnitude of the instantaneous [[velocity]] v, that is the derivative of the position r with respect to [[time]]: |