Acceleration

Acceleration is the rate of change of speed. To accelerate quickly (high acceleration) is to have a change of speed in a period of time. To accelerate slowly (low acceleration) is to have a change of speed in a period of time.

a = Change in speed = Δ v = v - u time t t

where a = Acceleration in metres per second per second, m/s/s or m/s2 or ms-2 v = Final speed in metres per second, m/s or ms-1 u = Initial speed in metres per second, m/s or ms-1 t = Time in Seconds, s

This can be summarised in the following 'magic triangle':

A acceleration means the object is slowing down i.e. the final speed, v is less than the initial speed, u. This type of change in motion is given a number of names: Slowing down; Decelerating and; Retardation. The particular name used depends on the particular situation.