Given data:
Initial speed of the runner as he starts from the rest;
[tex]u=0[/tex]Final speed of the runner;
[tex]v=12\text{ m/s}[/tex]Time taken;
[tex]t=6.0\text{ s}[/tex]The acceleration of the runner is given as,
[tex]a=\frac{v-u}{t}[/tex]Substituting all known values,
[tex]\begin{gathered} a=\frac{(12\text{ m/s})-0}{(6.0\text{ s})} \\ =2\text{ m/s}^2 \end{gathered}[/tex]Therefore, the acceleration of the runner is 2 m/s².