Kinematics of motion in a straight line — practice question

A particle is released from rest at point $O$ and travels along a horizontal straight line. At time $t\text{ s}$ after leaving $O$, its velocity is $v\text{ m s}^{-1}$. When $0 \le t < 60$, the velocity is given by $v = 0.05t - 0.0005t^2$. At $t = 60$, the particle strikes a wall and then changes the direction of its motion. It later comes to rest at point $A$ when $t = 100$, and for $60 < t \le 100$ the velocity is given by $v = 0.025t - 2.5$.