speed

1. Physics. The rate or a measure of the rate of motion, especially:
   1. Distance traveled divided by the time of travel.
   2. The limit of this quotient as the time of travel becomes vanishingly small; the first derivative of distance with respect to time.
   3. The magnitude of a velocity.
2. Swiftness of action.
3. 1. The act of moving rapidly.
   2. The state of being in rapid motion; rapidity.
4. A transmission gear or set of gears in a motor vehicle.
5. 1. A numerical expression of the sensitivity of a photographic film, plate, or paper to light.
   2. The capacity of a lens to accumulate light at an appropriate aperture.
   3. The length of time required or permitted for a camera shutter to open and admit light.
6. Slang. A stimulant drug, especially amphetamine or methamphetamine.
7. Slang. One that suits or appeals to a person's inclinations, skills, or character: Living in a large city is not my speed.
8. Archaic. Prosperity; luck.

1. To cause to go, move, or proceed quickly; hasten.
2. To increase the speed or rate of; accelerate: speed up a car; sped production.
3. To wish Godspeed to.
4. To further, promote, or expedite (a legal action, for example).
5. Archaic. To help to succeed or prosper; aid.

1. 1. To go, move, or proceed quickly: sped to the rescue.
   2. To drive at a speed exceeding a legal limit: was speeding on the freeway.
2. To pass quickly: The days sped by. The months have sped along.
3. To move, work, or happen at a faster rate; accelerate: His pulse speeded up.
4. Archaic.
   1. To prove successful; prosper.
   2. To get along in a specified manner; fare.

up to speed

1. 1. Operating at maximum speed.
   1. Producing something or performing at an acceptable rate or level.
2. InformalFully informed of or conversant with:I'm not up to speed on these issues yet. Fully informed of or conversant with: I'm not up to speed on these issues yet.

[Middle English spede, from Old English spēd, success, swiftness.]

SYNONYMS   speed, hurry, hasten, quicken, accelerate, precipitate. These verbs mean to proceed or cause to proceed rapidly or more rapidly. Speed refers to swift motion or action: The train sped through the countryside. Postal workers labored overtime to speed delivery of the holiday mail. Hurry implies a markedly faster rate than usual, often with concomitant confusion or commotion: Hurry, or you'll miss the plane! Don't let anyone hurry you into making a decision. Hasten suggests urgency and often eager or rash swiftness: My doctor hastened to reassure me that the tests were negative. His off-color jokes only hastened his dismissal. Quicken and especially accelerate refer to increase in rate of activity, growth, or progress: The skater's breathing quickened as he neared the end of his routine. The runner quickened her pace as she drew near the finish line. The economic expansion has continued but is no longer accelerating. Heat greatly accelerates the deterioration of perishable foods. Precipitate implies causing something to happen abruptly or prematurely: Mention of the issue precipitated an angry outburst during the meeting. See also synonyms at haste.

WORD HISTORY   We learn from the fable of the tortoise and the hare that the race is not always to the swift, but etymology teaches us that speed and success are closely related. The Old English word spēd, from which our word speed is descended, originally meant "prosperity, successful outcome, ability, or quickness." A corresponding verb, spēdan, in Modern English the verb speed, meant "to succeed, prosper, or achieve a goal"; and an adjective, spēdig, the ancestor of our word speedy, meant "wealthy, powerful." Except for archaic uses the words today relate only to the general sense of "velocity." The meaning "success" is retained chiefly in the compound Godspeed, a noun formed from the phrase meaning "May God cause you to prosper."

The time rate of change of position of a body without regard to direction. It is the numerical magnitude only of a velocity and hence is a scalar quantity. Linear speed is commonly measured in such units as meters per second, miles per hour, or feet per second.

Average linear speed is the ratio of the length of the path traversed by a body to the elapsed time during which the body moved through that path. Instantaneous speed is the limiting value of the foregoing ratio as the elapsed time approaches zero. See also Velocity.

Shorthand reference for prepayment of mortgages underlying mortgage-backed securities. There are various mathematical formulas for calculating loan prepayment that directly influence the calculated Yield to Maturity on mortgage-backed securities: Constant Percent Prepayment (CPP), an annualized estimate of mortgage prepayments; Constant Prepayment Rate (CPR), measuring prepayments as a ratio to outstanding mortgages. A prepayment assumption forecasts projected cash flows when a Colleralized Mortgage Obligation (CMO) initially is priced and offered to investors. As the CMO portfolio ages, these cash flows in turn determine the expected maturity (duration) and Average Life of the issue.

The ability to execute movements quickly. Speed is a component of physical fitness and refers to distance travelled per unit of time. During running and walking, speed is a product of stride length and stride rate (cadence). Stride length depends partly on flexibility and strength. Stride rate depends on the speed of muscular contractions. See also sprint.

noun

1. Rate of motion or performance: pace, tempo, velocity. Informal clip¹. See fast/slow/velocity.
2. Rapidness of movement or activity: celerity, dispatch, expedition, expeditiousness, fleetness, haste, hurry, hustle, quickness, rapidity, rapidness, speediness, swiftness. See fast/slow/velocity.

verb

1. To increase the speed of. accelerate, expedite, hasten, hurry, hustle, quicken, step up. See fast/slow/velocity.
2. To move swiftly: bolt, bucket, bustle, dart, dash, festinate, flash, fleet, flit, fly, haste, hasten, hurry, hustle, pelt², race, rocket, run, rush, sail, scoot, scour², shoot, sprint, tear¹, trot, whirl, whisk, whiz, wing, zip, zoom. Informal hotfoot, rip. Slang barrel, highball. Chiefly British nip¹. Idioms: get a move on, get cracking, go like lightning, go like the wind, hotfoot it, make haste, make time, make tracks, run like the wind, shake a leg, stepjumpon it. See move/halt.

Idioms beginning with speed:
speed up

In addition to the idiom beginning with speed, also see full speed ahead; up to par (speed).

Definition: rate
Antonyms: amble

v

Definition: move along quickly
Antonyms: delay, halt, hinder, hold up, slow, slow down

Relative rapidity of action; rate of motion.

1. Distance travelled per unit time, measured in metres per second. It is a scalar quantity. In running and walking speed is a product of stride length and stride rate.

2. The ability to perform a movement quickly. Speed of movement of either the total body (e.g. in sprinting) or of a particular body part is an important component of performance related fitness (see also reaction time). See amphetamines.

Quotes:

"Speed, it seems to me, provides the one genuinely modern pleasure." - Aldous Huxley

"Speed is scarcely the noblest virtue of graphic composition, but it has its curious rewards. There is a sense of getting somewhere fast, which satisfies a native American urge." - James Thurber

This article is about the property of moving bodies. For other uses, see Speed (disambiguation).

Classical mechanics

Newton's Second Law

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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.

Contents 1 Definition 2 Units 3 Examples of different speeds 4 See also 5 References

Definition

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:

Units

Main article: Conversion of units#Speed or velocity

Units of speed include:

• meters per second, (symbol m s⁻¹ or m/s), the SI derived unit
• kilometers per hour, (symbol km/h)
• miles per hour, (symbol mph)
• knots (nautical miles per hour, symbol kt)
• Mach number, speed divided by the speed of sound
• speed of light in vacuum (symbol c) is one of the natural units

c = 299,792,458 m/s

Conversions between common units of speed

	m/s	km/h	mph	knot
1 m/s =	1	3.6	2.234	1.944
1 km/h =	0.278	1	0.621	0.540
1 mph =	0.447	1.609	1	0.869
1 knot =	0.514	1.852	1.151	1

(Values in bold face are exact.)

Examples of different speeds

Main article: Orders of magnitude (speed)

• Speed of a common snail = 0.001 m/s; 0.004 km/h; 0.002 mph (1 millimeter per second).
• A brisk walk = 1.7 m/s; 6 km/h; 4 mph (5.5 feet per second).
• Olympic sprinters (average speed over 100 metres) = 10 m/s; 36 km/h; 22 mph.
• Speed limit on a French autoroute = 36 m/s; 130 km/h; 80 mph.
• Taipei 101 observatory elevator = 1010 m/min ; 16.7 m/s ; 60.6 km/h; 37.6 mph
• Cruising speed of a Boeing 747-8 = 290 m/s; 1050 km/h; 650 mph; (Mach 0.85)
• The speed of sound in dry air at sea-level pressure and 20 °C (293 kelvin) = 343 ms^-1 ≈ 1235 km/h ≈ 768 mph ( = Mach 1 by definition).
• Muzzle velocity of an AK47 assault rifle = 710 m/s; 2,600 km/h; 1,600 mph.
• Muzzle velocity of a paintball marker = 90 m/s; 320 km/h; 200 mph.
• Official flight airspeed record = 980 m/s; 3,530 km/h; 2,194 mph.
• Escape velocity on Earth: 11.2 km/s; 40,000 km/h; 25,000 mph
• Space shuttle on re-entry = 7,800 m/s; 28,000 km/h; 17,500 mph.
• Average orbital speed of planet Earth = 29,783 m/s; 107,218 km/h; 66,623 mph.
• Speed of light in vacuum (symbol c) 299,792,458 m/s (exactly, by definition of meter).

See also

Look up speed or swiftness in Wiktionary, the free dictionary.

• Air speed
• Land speed
• List of vehicle speed records
• Typical projectile speeds
• Speedometer
• V speeds

References

• Richard P. Feynman, Robert B. Leighton, Matthew Sands. The Feynman Lectures on Physics, Volume I, Section 8-2. Addison-Wesley, Reading, Massachusetts (1963). ISBN 0-201-02116-1.

Wikiquote has a collection of quotations related to: Speed

v • d • e Kinematics ← Integrate … Differentiate → Displacement (Distance) | Velocity (Speed) | Acceleration | Jerk | Jounce | Crackle and pop

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Dansk (Danish)
n. - hastighed, fart, gear, speed, amfetamin
v. tr. - forcere, sende hurtigt, udsende
v. intr. - køre for hurtigt, ile, trives

idioms:

• at speed    i stærk fart
• speed bump    hastighedsreducerende bump
• speed check    hastighedskontrol
• speed hump    hastighedsreducerende bump
• speed limit    hastighedsgrænse, fartgrænse, fartbegrænsning
• speed up    sætte farten op
• turn of speed    hastighedsændring

Nederlands (Dutch)
snelheid, vaart, drugs, zich spoeden, hard rijden, te hard rijden

Français (French)
n. - vitesse, rapidité, (Aut) vitesse, (Phot) sensibilité, vitesse d'obturation, speed (drogue), amphétamines
v. tr. - hâter, rendre (qch) plus fluide
v. intr. - aller à toute allure ou à toute vitesse, foncer, conduire trop vite

idioms:

• at speed    à toute vitesse
• get up speed    être au niveau
• speed bump    ralentisseur
• speed check    contrôle de vitesse
• speed hump    ralentisseur
• speed limit    limitation de vitesse
• speed up    aller plus vite, accélérer, accélérer l'allure, travailler plus vite, rendre plus fluide
• turn of speed    pleins gaz

Deutsch (German)
n. - Geschwindigkeit, Schnelligkeit, Gang, (Licht)empfindlichkeit, Belichtungszeit, Lichtstärke, Speed (Droge)
v. - schnell fahren, wegschicken

idioms:

• at speed    schnell
• get up speed    schneller werden
• speed bump    Bodenschwelle
• speed check    Geschwindigkeitskontrolle
• speed hump    Bodenschwelle
• speed limit    Geschwindigkeitsbegrenzung
• speed up    sich beeilen, beschleunigen
• turn of speed    hohe Geschwindigkeit bei Bedarf

Ελληνική (Greek)
n. - ταχύτητα, γρηγοράδα, σπουδή, (απαρχ.) ευόδωση, (καθομ.) μεθαμφεταμίνη, βαθμός φωτοευαισθησίας υγρού εμφανίσεως φωτογραφιών
v. - σπεύδω, τρέχω, κινούμαι με ταχύτητα, επισπεύδω, επιταχύνω, προωθώ

idioms:

• at speed    με (μεγάλη) ταχύτητα, ολοταχώς
• pick up speed    αναπτύσσω ταχύτητα
• speed bump    σαμαράκι
• speed check    έλεγχος υπερβολικής ταχύτητας
• speed hump    σαμαράκι
• speed limit    όριο ταχύτητας
• speed up    επιταχύνω, επισπεύδω
• turn of speed    ευελιξία, ικανότητα να κινηθεί γρήγορα

Italiano (Italian)
precipitarsi, andare in fretta, marcia, velocità

idioms:

• speed bump/hump    traversina di rallentamento
• speed check    controllo di velocità
• speed limit    limite di velocità
• speed up    accelerare

Português (Portuguese)
n. - marcha (f), velocidade (f), presteza (f)
v. - lançar, expedir

idioms:

• at speed    em movimento, com velocidade
• speed bump/hump    bandas sonoras
• speed check    verificação de velocidade
• speed limit    limite de velocidade
• speed up    aumento de velocidade
• turn of speed    diminuir velocidade

Русский (Russian)
скорость, быстрота, число оборотов, передача, быстродействие, светосила (объектива), светочувстви- тельность (пленки) быстро проходить, проноситься, мчаться, превышать дозволенную скорость, торопиться, ускорять, увеличивать число оборотов, регулировать скорость, быстро отсылать, способствовать (чему-л.)

idioms:

• at speed    со скоростью
• speed bump/hump    асфальтовый гребень поперек проезжей части
• speed check    прибор для определения скорости автомобиля
• speed limit    дозволенная скорость, предельная скорость (езды), предел числа оборотов
• speed up    убыстряться производить ускоренным темпом
• turn of speed    переключение скоростей, снижение скорости, быстрота

Español (Spanish)
n. - marcha, rapidez, velocidad, ritmo
v. tr. - prosperar, favorecer, ayudar, desear buena suerte, acelerar, apresurar, dar prisa, hacer correr
v. intr. - apresurarse, apurarse, prosperar, tener buen éxito, darse prisa, correr

idioms:

• at speed    a la mayor velocidad posible
• get up speed    acelerar
• speed bump    guardia tumbado, lomo de burro, badén, tope
• speed check    control de velocidad
• speed hump    guardia tumbado, lomo de burro, badén, tope
• speed limit    velocidad máxima, límite de velocidad
• speed up    acelerar, activar, dar prisa a
• turn of speed    buena aceleración

Svenska (Swedish)
n. - hastighet, fart, hastighetsgrad, växel
v. - ila, löpa, jaga, skjuta i väg, överskrida fartgränsen

中文（简体）(Chinese (Simplified))
迅速, 速率, 速度, 快速传送, 使加速, 促进, 加速, 快进, 超速

idioms:

• at speed    高速地
• speed bump    使车子减速行驶的路面突起
• speed check    取缔超速驾车的警察或自动测速照相装置, 汽车速度的检查
• speed hump    使车子减速行驶的路面突起
• speed limit    速度限制, 速度极限
• speed up    加快速度
• turn of speed    发挥速度的能力, 高速能力

中文（繁體）(Chinese (Traditional))
n. - 迅速, 速率, 速度
v. tr. - 快速傳送, 使加速, 促進
v. intr. - 加速, 快進, 超速

idioms:

• at speed    高速地
• speed bump    使車子減速行駛的路面突起
• speed check    取締超速駕車的警察或自動測速照相裝置, 汽車速度的檢查
• speed hump    使車子減速行駛的路面突起
• speed limit    速度限制, 速度極限
• speed up    加快速度
• turn of speed    發揮速度的能力, 高速能力

한국어 (Korean)
n. - 속력, 빠름, 각성제
v. tr. - 서두르게 하다, 진척시키다, (기계 따위의) 속도를 빠르게 하다
v. intr. - 급히 가다, 속도를 빠르게 하다, 성공 시키다

idioms:

• at speed    서둘러, 급히
• speed up    (기계따위의) 능률촉진, 속력증가, 노동 강화
• turn of speed    갑작스런 속도 증가

日本語 (Japanese)
n. - 速力, 勢力, 速度, シャッタースピード, 集光能力, 変速装置, 能力に合ったもの
v. - 急ぐ, 違反速度を出す, 加速度的に進行する, 急がせる, 速度を速める, 帰るのを送る, 放つ

idioms:

• at speed    急いで
• cruising speed    巡航速度
• speed bump/hump    減速バンプ
• speed check    速度チェック
• speed limit    制限速度
• speed up    速度を増す, 速度を上げる

العربيه (Arabic)
‏(الاسم) سرعه, نوع من المخدرات (فعل) يسرع, يعجل‏

עברית (Hebrew)
n. - ‮מהירות, הילוך, סמי מרץ‬
v. tr. - ‮שילח, שיגר‬
v. intr. - ‮מיהר, אץ, נע מהר, נסע במהירות, חלף‬

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