Hi guys, I've been looking on the internet all day for a satisfactory solution to this 2d problem but haven't found anything that makes sense. Let's say I have a sphere. In fact lets call it a ball with a mass m and it hits the ground with a velocity vy0 and vx0, the ball also has an angular velocity of w0 when it hits the ground. Let's say the frictional coefficient u or horizontal coefficient of restitution ex for the ground is known. What will be the post collision vx1 and angular w1 velocities? How are these determined? Does the change in angular velocity somehow effect the linear velocity by transferring kinetic energy through the ground? This problem is driving me nuts the closest thing I have found is a topic in my book which works though the problem without an initial angular velocity and this link about Garwins model. http://web.kellegous.com/ecrits/000858" [Broken] Any help on this would be greatly appreciated. Thanks, Matthew.