The existence of acceleration was given by Galileo in his different thoughts.
Acceleration of a body can be expressed as the rate of change of velocity with time. By acceleration, we can understand that how fast or slow the velocity of an object is changing.
Acceleration is a vector quantity. Its SI unit is m/s² and dimensional formula is [M⁰L¹T⁻²].
The average acceleration over a time interval is defined as the change in velocity divided by the time interval.
Let at any time (t₁) a body has velocity (v₁). At a letter time (t₂) it has velocity (v₂), Thus
Change in velocity ∆v = v₂-v₁
Change in time ∆t = t₂-t₁
If an object is moving with uniform acceleration, it means that the change in velocity is equal for equal interval of time.
If an object has non uniform acceleration, it means that the change in velocity is unequal in equal interval of time.
It is defined as the acceleration of a body at a certain instant or the limiting value of average acceleration, when time interval become very small or tends to zero.