The formula for velocity vf = vi + at
First list your given information
2m/s Is your initial velocity (vi)
6m/s is you final velocity (vf)
2 seconds is your time (t)
Since you want the a for acceleration get a by itself
a = (vf-vi)/t
So a= (6-2)/2
a= 4/2
a=2
Now units
the units for acceleration are m/s[tex] x^{2} [/tex]
2m/s[tex] x^{2} [/tex]