A cart with mass 320 g moving on a frictionless linear air track at an initial speed of 1.9 m/s undergoes an elastic collision with an initially stationary cart of unknown mass. After the collision, the first cart continues in its original direction at 1.18 m/s. What is the mass of the second cart? What is its (second cart) speed after impact? What is the speed of the two-cart center of mass?