The formula for acceleration is:
a = (Vf - Vi) / t
Where:
a = acceleration
Vf = final velocity
Vi = initial velocity
t = time
(Note that the formula can also be written using V, Velocity, and V0, Velocity Nought/zero. Its the same as final and initial velocity, with initial being nought)
We have all we need to do the problem now:
Vf = 20 m/s
Vi = 5 m/s
t = 3s
a = (20 - 5) / 3
a = 5 m/s^2
