This lecture discusses the kinetic energy and motion equations of two rotating discs connected by a bar. It covers the Lagrangian formalism, rolling without slipping conditions, and the balance of forces. The instructor explains the methods to model the system, calculate angular momentum, and solve for the angle of rotation. Various points on the discs are considered to analyze the system's energy and motion. The lecture concludes with the derivation of a differential equation to determine the angle of rotation over time.