A group of physics students is conducting an experiment using an air track. They have a 35 cm long massless spring with a spring constant of 10 N/m attached to the track at one end and an air track car of mass 320 g at the other end. The air track car is initially at rest. The students launch a second air track car of mass 600 g, towards the first. When the second air track car collides with the first, it sticks to it, causing the spring to compress by a distance of 20.0 cm from its natural length. Determine the velocity of the 600 g air track car right before the collision.