Everything You Need to Know About the Double Pendulum #SoMEpi

Abide by Reason derives the double pendulum equations for viewers familiar with Newton’s second law who want to see the power of the Lagrangian approach on a nontrivial system.

Abide by Reason briefly motivates the principle of least action for viewers who have seen forces and accelerations but not yet the variational foundation underlying much of modern physics.

Abide by Reason explores the small‑angle regime for viewers familiar with simple pendulum motion who want to see how the double pendulum reduces to coupled oscillators.

Abide by Reason uses the double pendulum to demonstrate chaos for viewers who have heard that deterministic systems can be unpredictable but have not seen a concrete mechanical example.