Rod OA rotates counterclockwise with a constant angular velocity of 5 rad/s. The double collar B is pin-connected together such that one collar slides over the rotating rod and the other slides over the horizontal curved rod, of which the shape is described by the equation r = 1.5(2 - cosq) ft. If both collars weight 0.75 lb, determine the normal force which the curved rod exerts on one collar at the instant = 120o.