Force examples.svg
Forces can be described as a push or pull on an object. They can be due to phenomena such as gravity, magnetism, or anything that might cause a mass to accelerate.
Common symbols
F, F, F
SI unitnewton (N)
Other units
dyne, pound-force, poundal, kip, kilopond
In SI base unitskg·m/s2
Derivations from
other quantities
F = m a

In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F.

The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.

Concepts related to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the internal mechanical stress. Such internal mechanical stresses cause no acceleration of that body as the forces balance one another. Pressure, the distribution of many small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of solid materials, or flow in fluids.

Development of the concept

Philosophers in antiquity used the concept of force in the study of stationary and moving objects and simple machines, but thinkers such as Aristotle and Archimedes retained fundamental errors in understanding force. In part this was due to an incomplete understanding of the sometimes non-obvious force of friction, and a consequently inadequate view of the nature of natural motion.[1] A fundamental error was the belief that a force is required to maintain motion, even at a constant velocity. Most of the previous misunderstandings about motion and force were eventually corrected by Galileo Galilei and Sir Isaac Newton. With his mathematical insight, Sir Isaac Newton formulated laws of motion that were not improved for nearly three hundred years.[2] By the early 20th century, Einstein developed a theory of relativity that correctly predicted the action of forces on objects with increasing momenta near the speed of light, and also provided insight into the forces produced by gravitation and inertia.

With modern insights into quantum mechanics and technology that can accelerate particles close to the speed of light, particle physics has devised a Standard Model to describe forces between particles smaller than atoms. The Standard Model predicts that exchanged particles called gauge bosons are the fundamental means by which forces are emitted and absorbed. Only four main interactions are known: in order of decreasing strength, they are: strong, electromagnetic, weak, and gravitational.[3]:2–10[4]:79 High-energy particle physics observations made during the 1970s and 1980s confirmed that the weak and electromagnetic forces are expressions of a more fundamental electroweak interaction.[5]

Other Languages
Afrikaans: Krag
Alemannisch: Kraft
አማርኛ: ጉልበት
العربية: قوة
aragonés: Fuerza
অসমীয়া: বল
asturianu: Fuercia
تۆرکجه: گوج
বাংলা: বল
Bân-lâm-gú: La̍t
башҡортса: Көс
беларуская: Сіла
беларуская (тарашкевіца)‎: Сіла (фізычная велічыня)
भोजपुरी: बर
български: Сила
Boarisch: Kroft
bosanski: Sila
буряад: Хүсэн
català: Força
čeština: Síla
chiShona: Manikidzo
Cymraeg: Grym
dansk: Kraft
Deutsch: Kraft
eesti: Jõud
Ελληνικά: Δύναμη
español: Fuerza
Esperanto: Forto
estremeñu: Huerça
euskara: Indar
فارسی: نیرو
Fiji Hindi: Taagat
français: Force (physique)
Gaeilge: Fórsa
Gaelg: Forse
galego: Forza
ગુજરાતી: બળ
客家語/Hak-kâ-ngî: Li̍t
한국어: 힘 (물리)
հայերեն: Ուժ
हिन्दी: बल (भौतिकी)
hrvatski: Sila
Ido: Forco
Bahasa Indonesia: Gaya (fisika)
interlingua: Fortia
isiXhosa: Ifolokhwe
íslenska: Kraftur
italiano: Forza
Kabɩyɛ: Ɖoŋ
ಕನ್ನಡ: ಬಲ
ქართული: ძალა
қазақша: Күш
Kiswahili: Kani
Kreyòl ayisyen: Fòs
kurdî: Hêz
Latina: Vis
latviešu: Spēks
lietuvių: Jėga
Limburgs: Krach
Luganda: Force
lumbaart: Forza
magyar: Erő
македонски: Сила
മലയാളം: ബലം
मराठी: बल
مازِرونی: نیرو
Bahasa Melayu: Daya (fizik)
монгол: Хүч
မြန်မာဘာသာ: အား
Nederlands: Kracht
नेपाली: बल
नेपाल भाषा: तिबः
日本語: 力 (物理学)
Nordfriisk: Krääft (füsiik)
norsk: Kraft
norsk nynorsk: Kraft
occitan: Fòrça
ଓଡ଼ିଆ: ବଳ
oʻzbekcha/ўзбекча: Kuch
ਪੰਜਾਬੀ: ਜ਼ੋਰ
پنجابی: زور
Patois: Fuos
ភាសាខ្មែរ: កម្លាំង
polski: Siła
português: Força
Qaraqalpaqsha: Ku'sh
română: Forță
Runa Simi: Kallpa
русиньскый: Сила
русский: Сила
संस्कृतम्: परस्परक्रिया
sardu: Fortza
shqip: Forca
sicilianu: Forza
සිංහල: බලය
Simple English: Force
slovenčina: Sila
slovenščina: Sila
Soomaaliga: Awood
српски / srpski: Сила
srpskohrvatski / српскохрватски: Sila
Sunda: Gaya
svenska: Kraft
Tagalog: Puwersa
தமிழ்: விசை
Taqbaylit: Tadusi
татарча/tatarça: Köç
తెలుగు: బలం
ไทย: แรง
тоҷикӣ: Нерӯ
Türkçe: Kuvvet
українська: Сила
اردو: قوت
vèneto: Forsa
Tiếng Việt: Lực
Winaray: Kusog
ייִדיש: קראפט