A 5.0 kg box, starting from rest, slides down a 5.0 m high frictionless hill, then across a 2.0 m wide horizontal surface, and finally hits a horizontal spring with spring constant 500 N/m. The other end of the spring is anchored against a wall. The ground under the spring is frictionless, but the 2.0 m wide horizontal surface is rough. The coefficient of kinetic friction of the box on this surface is 0.25. What is the speed of the box just before hitting the spring?