Acceleration is the rate of change of the velocity. If Dv is the change in velocity in a time interval Dt, then the average acceleration over that time interval is
The instantaneous acceleration is defined as the average acceleration taken in the limit of very small time intervals:
Like velocity, acceleration is a vector quantity. Its is indicated by its algebraic sign.
The instantaneous acceleration can be found as the slope of the tangent to the curve on an v versus t graph at that particular time.