5. A 1.8 kg cart moving at 9.0 m/s [E] collides with a stationary 1.2 kg cart. The head-on collision is completely elastic and is cushioned by a spring. The maximum compression of the spring during the collision is 3.0 cm. Find the spring constant. (6 marks) 6. Object 1 (with a mass of 3.0 kg), moving at 15.0 m/s [E], collides with object 2 (with a mass of 2.0 kg), initially at rest on a horizontal frictionless surface. The collision is a glancing one, with object 1 moving off at 11 m/s [E 30 N], after the collision. Assume that friction is negligible. Find the velocity of object 2 after the collision. (7 marks)