Used to be third-year in the major under Classical Mechanics. There's a good series of videos on YT, with the title Variational Calculus and the Euler-Lagrange

Used to be third-year in the major under Classical Mechanics. There's a good series of videos on YT, with the title Variational Calculus and the Euler-Lagrange equation on channel Structural Dynamics. I have only seen the first few. This first video should give you the full playlist: https://www.youtube.com/watch?v=VCHFCXgYdvY https://www.youtube.com/watch?v=VCHFCXgYdvY