# Acceleration | Definition, Types, Formulas, Units – Motion in a Straight Line

Acceleration Definition
The rate of change of velocity with time is called acceleration.
Acceleration Formula

$$Acceleration (a)=\frac{\text { Change in velocity }(\Delta v)}{\text { Time interval }(\Delta t)}$$

## Acceleration | Definition, Types, Formulas, Units – Motion in a Straight Line

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Acceleration Units

• Its SI unit is m/s².
• Its dimensional formula is [M°LT-2].
• It is a vector quantity.

Acceleration can be positive, zero or negative. Positive acceleration means velocity increasing with time, zero acceleration means velocity is uniform while negative acceleration (retardation) means velocity is decreasing with time.

Uniform Acceleration Definition:
If an object is moving with uniform acceleration, it means that the change in velocity is equal for equal interval of time.

Non-uniform Acceleration Definition:
If an object is moving with non-uniform acceleration, it means that the change in velocity is unequal for equal interval of time.

Average Acceleration Definition:
If a particle is accelerated for a time t1 with acceleration a1, and for a time t2 with acceleration a2, then average acceleration

$$a_{\mathrm{av}}=\frac{a_{1} t_{1}+a_{2} t_{2}}{t_{1}+t_{2}}$$

Instantaneous Acceleration Definition:
It is defined as the acceleration of object at any instant of time.

$$a_{\text {inst }}=\lim _{\Delta t \rightarrow 0} \frac{\Delta v}{\Delta t}=\frac{d v}{d t}$$

Motion in a Straight Line Topics: