Acceleration

Acceleration is a measure of the rate of change of velocity... it measures how quickly the speed of a body changes.

It is calculated by dividing the change in velocity, Δv, by the time interval the change occurs in, Δt.

If we call the initial velocity 'u' and the final velocity 'v', then the change in velocity Δv = v - u

So,

The units are therefore the 'unit of velocity' divided by the 'unit of time':

(m/s)/s = m/s² or ms^-2

You can find acceleration from a velocity/time graph. You simply calculate the gradient of the graph.