Answer
$a_A= 0m/s^2$
Work Step by Step
Finding the acceleration of block A at rest:
Because the block is at rest we know that the static frictional force
is equal to the applied force on block A
$F_{net} = 0$
$m_Aa_A = 0$
$a_A = \frac{0}{m_A}$
$a_A= 0m/s^2$
