Kinematics of motion in a straight line — practice question

Particle $P$ travels along a straight line, beginning from rest at point $O$ on the line. Let $t$ s denote the time since $P$ began moving. The particle then moves along the line with constant acceleration $\frac{1}{4}\,\text{m s}^{-2}$ until it goes through point $A$ when $t = 8$. Once it has passed through $A$, the velocity of $P$ is $\frac{1}{2}t^{3/4}\,\text{m s}^{-1}.