# Velocity

Velocity
As a change of direction occurs while the racing cars turn on the curved track, their velocity is not constant.
Common symbols
v, v, v
Other units
mph, ft/s
In SI base unitsm/s
DimensionL T−1

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.

Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s) or as the SI base unit of (m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration.

## Constant velocity vs acceleration

To have a constant velocity, an object must have a constant speed in a constant direction. Constant direction constrains the object to motion in a straight path thus, a constant velocity means motion in a straight line at a constant speed.

For example, a car moving at a constant 20 kilometres per hour in a circular path has a constant speed, but does not have a constant velocity because its direction changes. Hence, the car is considered to be undergoing an acceleration.

Other Languages
Afrikaans: Snelheid
Alemannisch: Geschwindigkeit
አማርኛ: ፍጥነት
العربية: سرعة متجهة
aragonés: Velocidat
অসমীয়া: বেগ
asturianu: Velocidá
বাংলা: গতিবেগ
Bân-lâm-gú: Sok-tō͘
башҡортса: Тиҙлек
беларуская: Скорасць
беларуская (тарашкевіца)‎: Хуткасьць
български: Скорост
Boarisch: Gschwindigkeit
bosanski: Brzina
буряад: Хурдан
català: Velocitat
Чӑвашла: Хăвăртлăх
čeština: Rychlost
chiShona: Muchacha
Cymraeg: Cyflymder
dansk: Hastighed
eesti: Kiirus
Ελληνικά: Ταχύτητα
Esperanto: Vektora rapido
estremeñu: Velocidá
français: Vecteur vitesse
Frysk: Snelheid
Gaeilge: Treoluas
Gaelg: Bieauid
한국어: 속도
հայերեն: Արագություն
हिन्दी: वेग
hrvatski: Brzina
Bahasa Indonesia: Kecepatan
interlingua: Velocitate
isiXhosa: I-velocity
íslenska: Hraði
italiano: Velocità
עברית: מהירות
Basa Jawa: Kacepetan
ಕನ್ನಡ: ವೇಗ
қазақша: Жылдамдық
Kiswahili: Kasimwelekeo
Kreyòl ayisyen: Vitès mwayèn
Latina: Velocitas
Limburgs: Snelheid
lumbaart: Velocitaa
magyar: Sebesség
македонски: Брзина
മലയാളം: പ്രവേഗം
मराठी: वेग
Bahasa Melayu: Halaju
Mìng-dĕ̤ng-ngṳ̄: Sók-dô
монгол: Хурд
မြန်မာဘာသာ: အလျင်
Nederlands: Snelheid
नेपाली: गति

Nordfriisk: Faard
norsk: Hastighet
norsk nynorsk: Hastigheit
occitan: Velocitat
oʻzbekcha/ўзбекча: Tezlik
ਪੰਜਾਬੀ: ਵੇਗ
پنجابی: ولاسٹی
ភាសាខ្មែរ: ល្បឿន
Piemontèis: Andi
polski: Prędkość
română: Viteză
Runa Simi: Utqa kay
русиньскый: Швыдкость
русский: Скорость
Scots: Velocity
සිංහල: ප්‍රවේගය
Simple English: Velocity
slovenščina: Hitrost
српски / srpski: Брзина
srpskohrvatski / српскохрватски: Brzina
suomi: Nopeus
svenska: Hastighet