Blocks A and B are able to slide on a smooth surface. Block A has a mass of 30 kg. Block B has a mass of 60 kg. At a given instant, block A is moving to the right at 0.5 m/s, block B is moving to the left at 0.3 m/s, and the spring connected between them is stretched 1.5 m. Determine the speed of both blocks at the instant the spring becomes unstretched. 9.