I'm trying to write a 2-D snowboarding game. I've forgotten my simple physics from college. Anyway, the problem is... Say you have a snowboarder falling straight down at velocity V and being accelerated by Gravity G. Say snowboarder then lands on a slope of Angle 45 degrees. I want to now now what the snowboarder's new X and Y components for Velocity are. I know that the acceleration down the slope(parallel to the friction) due to gravity when on the slope is: A = G sin(Angle) And also I know that I have to account for friction so really this becomes: A = G (sin(Angle) - Friction(cos(Angle))) And, so I can calculate Ax and Ay. But, what is confusing me is I would think that when the snowboarder hits the ramp, the snowboarders Velocity in the Y direction would *decrease*, not increase as the above formula would suggest. So, what am I missing? I guess the incline pushes back somehow to slow down the rider so they don't go thru the ground. What's that equation? I feel that the snowboarders Velocity should somehow be in that equation? ie, if the snowboarder is dropping at a Vy rate of 10 meters/sec, the ground would push back harder in the -Vy direction, no? thanks!