1. The problem statement, all variables and given/known data I suppose my question is a broad one. I am writing a Physics Extended Essay for the IB program (approx. 4000 words). My research question is "How does the angle of an inclined plane impact the horizontal translational kinetic energy of a solid cylinder [after it impacts and bounces across a horizontal surface, probably a wooden table, given no slipping]?", though this is not the question I need answered. I am struggling to figure out how one might figure out theoretically how much KE the cylinder will lose due to the collisions (experimentally I can do this with a high speed camera). Is the KE lost to the collisions solely based on that of the vertical component, or is some of the horizontal component lost as well, or even the angular? Does the number of collisions matter? I do not have an experiment done yet, nor should I for this essay at this point, thus I have no numbers. If someone could direct me to a source, that would be fantastic. 2. Relevant equations Coefficient of Restitution Vy = mg*sinθ, where θ is the angle of incline 3. The attempt at a solution I am beginning to figure that the number of collisions is theoretically insignificant, though that is if the KE lost in the collision is solely that of the vertical component, where KE lost = .5m*(Vy)^2 = .5m(mg*sinθ)^2 Intuitively (which is a dangerous way to look at physics), I do not see the collisions having an effect on the horizontal component at any point.