Meriam, Kraige & Bolton — Plane Kinematics of Rigid Bodies: Problem 5_14

5/14 At time $t = 0$, the arm is rotating about the fixed $z$-axis with an angular velocity $\omega = 200 \text{ rad/s}$ in the direction shown. At that time, a constant angular deceleration begins and the arm comes to a stop in $10 \text{ seconds}$. At what time $t$ does the acceleration of point $P$ make a $15^\circ$ angle with the arm $AB$?