Dictionary:

acceleration

  (ăk-sĕl'ə-rā'shən)

1. 1. The act of accelerating.
   2. The process of being accelerated.
2. (Abbr. a) Physics. The rate of change of velocity with respect to time.

The time rate of change of velocity. Since velocity is a directed or vector quantity involving both magnitude and direction, a velocity may change by a change of magnitude (speed) or by a change of direction or both. It follows that acceleration is also a directed, or vector, quantity. If the magnitude of the velocity of a body changes from v₁ ft/s to v₂ ft/s in t seconds, then the average acceleration a has a magnitude given by Eq. (1):
1.
To designate it fully the direction should be given, as well as the magnitude. See also Velocity.

Instantaneous acceleration is defined as the limit of the ratio of the velocity change to the elapsed time as the time interval approaches zero. When the acceleration is constant, the average acceleration and the instantaneous acceleration are equal.

Whenever a body is acted upon by an unbalanced force, it will undergo acceleration. If it is moving in a constant direction, the acting force will produce a continuous change in speed. If it is moving with a constant speed, the acting force will produce an acceleration consisting of a continuous change of direction. In the general case, the acting force may produce both a change of speed and a change of direction.

Angular acceleration is a vector quantity representing the rate of change of angular velocity of a body experiencing rotational motion. If, for example, at an instant t₁, a rigid body is rotating about an axis with an angular velocity ω₁, and at a later time t₂, it has an angular velocity ω₂, the average angular acceleration α is given by Eq. (2), in radians per second per second.
2.
The instantaneous angular acceleration is given by α = dω/dt.

When a body moves in a circular path with constant linear speed at each point in its path, it is also being constantly accelerated toward the center of the circle under the action of the force required to constrain it to move in its circular path. This acceleration toward the center of path is called radial acceleration. The component of linear acceleration tangent to the path of a particle subject to an angular acceleration about the axis of rotation is called tangential acceleration. See also Rotational motion.

In real estate law: (1) hastening of the time for enjoyment of a remainder interest due to the premature termination of a preceding estate; and (2) process by which, under the terms of a Mortgage or similar obligation, an entire debt is to be regarded as due upon the borrower's failure to pay a single installment or to fulfill some other duty. See also Acceleration Clause.

Definition: increasing speed, timing
Antonyms: deceleration, deferral, hindrance, retardation, slowing down

For more information on acceleration, visit Britannica.com.

1. The rate of change of the velocity of a moving body.
2. The rate of change, esp. the quickening of the natural progress of a process, such as hardening, setting, or strength development of concrete.

The rate of change in velocity or the change in velocity occurring over a given time interval: acceleration = change of velocity/time. It is usually expressed as metres per second squared (ms⁻²). When an object speeds up, slows down, starts, stops, or changes direction, it is accele rating. Acceleration can be positive or negative. See also acceleration, law of.

A hastening; a shortening of the time until some event takes place.

A person who has the right to take possession of property at some future time may have that right accelerated if the present holder loses his or her legal right to the property. If a life estate fails for any reason, the remainder is accelerated.

The principle of acceleration can be applied when it becomes clear that one party to a contract is not going to perform his or her obligations. Anticipatory repudiation, or the possibility of future breach, makes it possible to move the right to remedies back to the time of repudiation rather than to wait for the time when performance would be due and an actual breach would occur.

A change in the velocity of an object.

Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point.

In physics, acceleration is defined as the rate of change of velocity, or, equivalently, as the second derivative of position. It is thus a vector quantity with dimension length/time². In SI units, acceleration is measured in metres/second² (m·s^-²). The term "acceleration" generally refers to the change in instantaneous velocity.

Relation to relativity

After completing his theory of special relativity, Albert Einstein realized that forces felt by objects undergoing constant proper acceleration are indistinguishable from those in a gravitational field. This was the basis for his development of general relativity, a relativistic theory of gravity.

This is also the basis for the popular Twin paradox, which asks why one twin ages more rapidly when moving away from his sibling at near light-speed and then returning, since the aging twin can say that it is the other twin that was moving. 

General relativity solved the "why does only one object feel accelerated?" problem which had plagued philosophers and scientists since Newton's time (and caused Newton to endorse absolute space). In special relativity, only inertial frames of reference (non-accelerated frames) can be used and are equivalent; general relativity considers all frames, even accelerated ones, to be equivalent. (The path from these considerations to the full theory of general relativity is traced in the Introduction to general relativity.)

Formulas

The formula for acceleration is

(Final Velocity - Initial Velocity / Total Time Taken)

See also

• Coordinate vs. physical acceleration
• Derivatives of position

References

• Serway, Raymond A.; Jewett, John W. (2004). Physics for Scientists and Engineers, 6th ed., Brooks/Cole. ISBN 0-534-40842-7. 
• Tipler, Paul (2004). Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics, 5th ed., W. H. Freeman. ISBN 0-7167-0809-4. 

External links

• Acceleration and Free Fall - a chapter from an online textbook
• Trajectories and Radius, Velocity, Acceleration on Project PHYSNET
• Science aid: Movement
• Physics Classroom: Acceleration
• Science.dirbix: Acceleration
• Acceleration Calculator
• Motion Characteristics for Circular Motion

Kinematics
← Integrate ... Differentiate → Displacement (Distance) | Velocity (Speed) | Acceleration | Jerk | Snap

nov:Akseleratione

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - acceleration, hastighedsforøgelse

Nederlands (Dutch)
versnelling, bespoediging

Français (French)
n. - accélération, (Fin) (clause) d'accélération, (Fin) remboursement, par déchéance du terme

Deutsch (German)
n. - Beschleunigung, Vorverlegung, Akzeleration

Ελληνική (Greek)
n. - επιτάχυνση, επίσπευση

Italiano (Italian)
accelerazione

Português (Portuguese)
n. - aceleração (f)

Русский (Russian)
ускорение

Español (Spanish)
n. - aceleración

Svenska (Swedish)
n. - acceleration

中文（简体） (Chinese (Simplified))
加速, 加速度, 促进

中文（繁體） (Chinese (Traditional))
n. - 加速, 加速度, 促進

한국어 (Korean)
n. - 촉진, 가속도

日本語 (Japanese)
n. - 加速, 促進, 加速度

العربيه (Arabic)
‏(الاسم) تسريع, تعجيل‏

עברית (Hebrew)
n. - ‮תאוצה, האצה‬

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