A 2 kg collar is attached to a spring and slides without friction in a vertical plane along the curved rod ABC. The spring is undeformed when the collar is at C and k = 600 N/m. If the collar is released at A with no initial velocity, determine its velocity (a) as it passes through B, (b) as it reaches C. (The spring is anchored at O on the horizontal line through A and C, with OC = 150 mm and OA = 250 mm; B is on the rod 200 mm directly below O.)