A 500 g collar can slide without friction on the curved rod BC in a horizontal plane. Knowing that the undeformed length of the spring is 80 mm and k = 400 kN/m, determine the velocity that the collar should be given at A to reach B with zero velocity. (In the given position the spring is 150 mm long when the collar is at A and 200 mm long when it is at B.) (answer in m/s)