Hi there! I'm not english, and i learned Physics in German, so i don't know how certain things are called. I am programming a Rigid Body Dynamics Engine for Macromedia Flash, and i'm often not sure how to name my variables. Well, how are the following things called in english? 1. The constant factor a spring has, which describes the force it applys (force = (relaxedLength-currentLength)*someFactor) 2. When a spring is compressed/extended, it can have some kind of damping or cushion. (It is calculated by the speed at which the spring is compressed) How would you call this factor (dampForce = compressionSpeed*strangeFactor) 3. Another factor, that decreases speed continously. (every time unit the speed is multiplied my a value between 0 and 1, it has some kind of air-friction effect, causing speed to move against 0) 4. in dynamics programming, first every force is accumulated, and then these forces are integrated (the moment of kinematics) how would you call the step of accumulating Forces, and the Step of making these forces change velocities? 5. The relaxed length of a spring ("relaxed" or "unstressed", ...) Of what expressions can you think? Thanks very much!