The uniform slender bar of mass m and length l is released from rest in the vertical pos...

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 θ = 30°, find the coefficient of static friction μ_s between the bar and the corner. (b) If the end of the bar is notched so that it cannot slip find the angle θ at which contact between the bar and the corner ceases.