Central Force Motion and Kepler Orbit Equation
upsc.abhi-physics.com/posts/central-force-motion-and-kepler-orbit-equation-f43b399a
Two-Body Central Force Problem
The equation of orbit under inverse-square law (r) = -k/r^2$ is: 2497747\frac{d^2 u}{d\theta^2} + u = \frac{m k}{L^2}2497747
Conic section solution: 2497747r(\theta) = \frac{p}{1 + e \cos\theta}2497747

Answers1
Excellent derivation of the Binet equation!