A block of inertia .2 kg is launched from a spring onto a frictionless surface. The velocity it has upon leaving the spring is 2.5 m/s. It rebounds from a wall at -2.0 m/s. Assume any energy loss occurred at the wall. If the spring is originally compressed by 6 cm, what is the force constant on the spring? What is the impulse delivered to the block by the wall?