9. (10 points) A young child pushes her stuffed plush cow down a frictionless slide at the playground. The slide has a height h. The cow exits the slide horizontally at the bottom. The cow slides along the level ground before coming to a stop a distance L away from the bottom of the slide. What is the coefficient of friction between the plush cow and the ground? Your answer should be expressed in terms of any of the variables given in the problem and any relevant physical constants