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cceleration, in physics, is the rate of change of velocity of an object. An

object's acceleration is the net result of any and all forces acting on the object,

as described by Newton's Second Law.[1 !he S" unit for acceleration is #etre

per second s$uared %#&s(. Accelerations arevector  $uantities %they

have #agnitude and direction( and add according to the parallelogra# law.[

[) As a vector , the calculated net forceis e$ual to the product of the object's

#ass %a scalar  $uantity( and the acceleration.

*or e+a#ple, when a car starts fro# a standstill %ero relative velocity( and

travels in a straight line at increasing speeds, it is accelerating in the direction

of travel. "f the car turns there is an acceleration toward the new direction. *or

this e+a#ple, we can call the accelerating of the car forward a -linear

acceleration-, which passengers in the car #ight e+perience as force pushing

the# bac into their seats. /hen changing directions, we #ight call this -non0

linear acceleration-, which passengers #ight e+perience as a sideways force.

"f the speed of the car decreases, this is an acceleration in the opposite

direction of the direction of the vehicle, so#eti#es called deceleration.

[2assengers #ay e+perience deceleration as a force lifting the# away fro#

their seats. 3athe#atically, there is no separate for#ula for deceleration, as

both are changes in velocity. 4ach of these accelerations %linear, non0linear,

deceleration( #ight be felt by passengers until their velocity %speed and

direction( #atch that of the car.

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Average acceleration[edit

 Acceleration is the rate of change of velocity. At any point on a trajectory, the #agnitude

of the acceleration is given by the rate of change of velocity in both #agnitude and

direction at that point. !he true acceleration at ti#e t  is found in the li#it as ti#e

interval  Δt  5 6 of  Δv& Δt 

 An object's average acceleration over a period of ti#e is its changein velocity  divided by the duration of the period .

3athe#atically,

Instantaneous acceleration[edit

From bottom to top7

• an acceleration function a%t (8

• the integral of the acceleration is the velocity function v %t (8

• and the integral of the velocity is the distance function s%t (.

"nstantaneous acceleration, #eanwhile, is the li#it of the average

acceleration over an infinitesi#al interval of ti#e. "n the ter#s of calculus,

instantaneous acceleration is the derivative of the velocity vector with

respect to ti#e7

%9ere and elsewhere, if #otion is in a straight line, vector  $uantities can

be substituted by scalars in the e$uations.(

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"t can be seen that the integral of the acceleration function a(t ) is the

velocity function v(t )8 that is, the area under the curve of an

acceleration vs. ti#e %a vs. t ( graph corresponds to velocity.

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