Definition: Countermutiny is a concept in physics that describes the phenomenon where two or more particles move in opposite directions at different speeds and angles, resulting in a net force acting on one of them. It is named after the German physicist Karl Heinz Jahnke who first described it as a "counterclockwise" motion. In this context, the term "countermutiny" refers to a situation where two or more particles move in opposite directions at different speeds and angles, resulting in