A slender bar AB with mass m and length l has small rollers mounted on the two ends. Initially the bar is at rest with θ = 45° and its motion is constrained by the x-y horizontal slots when a counterclockwise couple M is applied as shown in the figure. If m = 2 kg, l = 0.5 m, and M = 3 N·m, calculate the magnitude of the bar's angular acceleration as it starts to move. Present your answer in rad/sec^2 using 3 significant figures.