Acceleration
rate at which the magnitude and/or direction of velocity changes with time
In physics, acceleration is a measure of how fast and in what direction an object's speed and direction of motion are changing. It is defined as the rate of change of the velocity. Like velocity, acceleration has a magnitude and a direction, making it a vector quantity. The SI unit for acceleration is metre per second squared (m⋅s−2, m/s2).
The tangential acceleration of an object is the component of the acceleration which is in the same direction as the motion (or tangential velocity) of the object. When the velocity of the object does not change direction, this is called linear acceleration. Deceleration or retardation, on the other hand, is the component of the acceleration in the opposite (or antiparallel) direction to the tangential velocity. Radial acceleration or normal acceleration (or centripetal acceleration during circular motions) is the component of the acceleration that changes the direction of the object's velocity.
In Newtonian mechanics, the acceleration of a mass arises from forces acting on it, with its net acceleration being a result of the net force acting on it. By Newton's second law, the magnitude of the net acceleration will be proportional to the magnitude of the net force acting on the object and inversely proportional to the mass of the object, while the direction of the net acceleration will be the same as the direction of the net force.
This brief starts where responsible research should: with the source description of “Acceleration” as rate at which the magnitude and/or direction of velocity changes with time. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as rate at which the magnitude and/or direction of velocity changes with time. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 22, 2026. The linked authority identifier is Q11376. The Library of Congress control number is sh85000344. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
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This entry incorporates text from “Acceleration” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.