Two air carts of mass = 0.90 and = 0.44 are placed on a frictionless track. Cart 1 is at rest initially, and has a spring bumper with a force constant of 690 . Cart 2 has a flat metal surface for a bumper, and moves toward the bumper of the stationary cart with an initial speed = 0.64 . Assume that positive -axis is directed toward the direction of motion of cart 2.