A 30-lb slender rod AB is 5 ft long and is pivoted about a point O which is 1 ft from end B. The other end is pressed against a spring constant k = 1800 lb/in until the spring is compressed 1 inch. The rod is then in a horizontal position. If the rod is released from this position, determine a) its angular velocity, b) the reaction at the pivot O, as the rod passes through a vertical position.