"Pillar of the community" and creator of Chipmunk2D Scott Lembcke visits the clubhouse to talk velocity, constraints, and rigidbodies. Ellen gets the music in her head, Stephen didn’t learn the opposite lesson, and Mark makes a pretty good joke about friction.

Physics 101ProgrammingChipmunk2D - Scott Lembcke , GitHubGopher (protocol)Building Excalibur.js - Erik Onarheim, YouTube

I'm pretty sure this was the song stuck in Ellen's head.

What is an AABB? - Michael Rubloff, Radiance FieldsVeridian Expanse - Howling Moon Software, SteamIs pool actually just mathematics? - Stand-up Maths, YouTubeWhat is up with the spherical cow? - Rhett Allain, WiredAdvanced Character Physics - Thomas Jakobsen, Carnegie Mellon UniversityArc length of an ellipse - Ed Sandifer, The Euler ArchiveBox2D version 3.0 beta test has launched! - Erin Catto, MastodonTen Minute Physics - YouTube