Answer
$a_{net}=0.56 \frac{m}{sec^2}$
Work Step by Step
We know that
$F_{net}=F+(-f_k)$
where the negative sign shows that the applied force and force of friction are in opposite direction.
Therefore, $F_{net}=F-f_k$
We remember from Newton's second law that:
$F_{net}=ma_{net}$
Thus, the equation becomes
$ma_{net}=F-f_k$
$a_{net}=\frac{F-f_k}{m}$
Putting the values and solving:
$a_{net}=\frac{220-189}{55}$
$a_{net}=0.56 \frac{m}{sec^2}$
