An ideal spring is initially compressed and placed between two masses on a horizontal frictionless surface. The masses are not attached to the spring. The left mass is 7.0 kg and the right mass is 5.0 kg. After releasing the system from rest, the 7.0 kg mass travels at 10.0 m/s when it loses contact with the spring. The 5.0 kg mass travels at m/s when it loses contact with the spring?