Two identical 4-lb collars, A and B, are attached to a spring of constant 7 lb/ft and

Question:

Two identical 4-lb collars, A and B, are attached to a spring of constant 7 lb/ft and can slide on a horizontal rod which is free to rotate about a vertical shaft. Collar B is initially prevented from sliding by a stop as the rod rotates at a constant rate θ0 = 5 rad/s and the spring is in compression with rA = 3 ft and rB = 7.5 ft. After the stop is removed both collars move out along the rod. At the instant when rB = 9 ft, determine

(a) rA,

(b) θ,