Lecture
This lecture covers the central motion in a 1/r² field, focusing on writing Newton's equation in polar coordinates, using Binet's formula, and identifying the solution as an ellipse. The instructor explains the projection of Newton's equation onto e, the conservation of angular momentum, and the resemblance to the dynamics of a mass on a spring. The determination of trajectory parameters based on energy and angular momentum constants is discussed, along with the types of trajectories (ellipse, circle, parabola, hyperbola) determined by the value of K. The lecture concludes with the expression of mechanical energy and its independence of mass, emphasizing the kinetic and potential energy components.