4. A small brick of mass 0.5 kg is placed on a rough plane which is inclined to the horizontal at an angle \(\theta\), where \(\tan \theta = \frac { 4 } { 3 }\), and released from rest. The coefficient of friction between the brick and the plane is \(\frac { 1 } { 3 }\). Find the acceleration of the brick.
(9)