good guy.

I like the Vertasium youtube channel, and this one was particularly good.
https://www.youtube.com/watch?v=Q10_srZ-pbs&ab_channel=Veritasium

I had just got done teaching my grad robotics class about how to use the Euler-Lagrange method for derivation of dynamical equations (free body diagrams can burn in everlasting torment BTW), and then I saw this and it was a good supplement to that lecture.