There are analogous notions once we include relativity or quantum mechanics, but for our present purposes the version that Galileo and Newton would have recognized is good enough: in any interaction ...

A sphere moving on a smooth horizontal surface (the xy-plane) impacts a set of 13 cubes at rest on the same surface. This impacts leads to a number of subsequent impacts among these cubes. The ...

In a closed physical system, the sum of all angular momentum remains constant, according to an important physical law of conservation. Angular momentum does not necessarily need to involve "real" ...