Internal forces and angular momentum conservation

Abstract One of the main points of classical mechanics courses, the conservation law of angular momentum provides simple relations among different states of a system exhibiting rotational dynamics. Nonetheless, such approach fails to elucidate the internal processes that lead from one state to another. Filling this gap, we perform a different analysis of simple situations where angular momentum is conserved, focusing on the internal forces and torques of the analyzed systems when they change their rotational states. Such approach may prove itself useful for a deeper understanding of the observed dynamics, especially since the discussed situations are commonly seen in classroom demonstrations.