A 4 kg concentrated mass is attached to the end of a 9 kg uniform slender rod that is rotating in a vertical plane as shown. The rod AB is 2m long and has an angular velocity of 3 rad/s clockwise when it is vertical. If the undeformed length of the spring is 0.25 m, determine the spring constant such that the angular velocity of AB will be zero when the rod is horizontal. 1 mi 1m 0.1 m www Figure 3 Spor