Thanks to Java_Programmer for: Ball Collision Tutorial Ball+Line Collision Visual Explanations for 'Mode' slider variable: 1- position one Ball with the mouse and check collisions 2- jumping Balls with collision report; click anywhere to continue 3- Ball and Platform; slider variable 'stop at collision' 4, 5, 6, 7- as Java_Programmer's Ball Collision Tutorial 8- as Java_Programmer's Ball+Line Collision Visual 9- colliding Balls in a Platform (wait for Ball to stop on Platform)