Meriam, Kraige & Bolton — Plane Kinetics of Rigid Bodies: Problem 6_56

6/56 The uniform slender bar of mass $m$ and length $l$ is released from rest in the vertical position and pivots on its square end about the corner at $O$. (a) If the bar is observed to slip when $\theta = 30^\circ$, find the coefficient of static friction $\mu_s$ between the bar and the corner. (b) If the end of the bar is notched so that it cannot slip, find the angle $\theta$ at which contact between the bar and the corner ceases.