2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/85595A high-school exercise is used to get an insight into planetary motion.Revised and extended version. Alltogether 10 solutions of a high-school contest problem, including original proofs of Maxwell and of Newton, are presented. 11 pages, 4 eps figuresClassical PhysicsPhysics Educationtext