Halliday, Resnick & Walker — Rolling, Torque, and Angular Momentum: Problem 34

Figure 11-36 is an overhead view of a rod of length $d$ and negligible mass that rotates at angular speed $\omega$ in the horizontal plane about a vertical axis through point $O$. Particle $A$ of mass $m$ is attached at the center point and an identical particle $B$ is attached at the far end. Find the angular momentum of particle $B$ with respect to particle $A$.