Difference between revisions of "Speed"
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==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 [ | + | *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== | ||
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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 [ | + | 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 [ | + | 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 [ | + | 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]]: | ||
Latest revision as of 02:37, 13 December 2020
Etymology
Middle English spede, from 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 12th century
Definitions
- 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
- 3 : swiftness or rate of performance or action : velocity 3a
- 4 a : the sensitivity of a photographic film, plate, or paper expressed numerically b : the light-gathering power of a lens or optical system c : the time during which a camera shutter is open
- 5 : a transmission gear in automotive vehicles or bicycles —usually used in combination <a ten-speed bicycle>
- 6 : someone or something that appeals to one's taste <just my speed>
- 7 : methamphetamine; also : a related stimulant drug and especially an amphetamine
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 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 SI unit of speed is the meter per second, but the most usual unit of speed in everyday usage is the kilometer per hour or, in certain countries, the mile per hour.
The fastest possible speed at which energy or information can travel, according to 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:
If s is the length of the path traveled until time t, the speed equals the time derivative of s:
