Changes

==Etymology==

==Etymology==

[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]]

[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>

<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==

*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 .

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].

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

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]]: