The compound pendulum is composed of a uniform slender rod of length l and mass 2m to wh...

The compound pendulum is composed of a uniform slender rod of length l and mass 2m to which is fastened a uniform disk of diameter l /2 and mass m. The body pivots freely about a horizontal axis through O. If the pendulum has a clockwise angular velocity of 3 rad /s when Θ = 0 at time t = 0, determine the time t at which the pendulum passes the position Θ = 90°. The pendulum length l = 0.8 m.