I am a third of the way through the first of the four dialogues. It consists largely of showing how cumbersome and inconsistent Aristotelian physics is. It is a hard slog. We owe Galileo a debt for taking down Aristotle, cleaning the slate, and then starting to fill it in with new physics so that Newton could complete mechanics.
There is a little bit of actual physics. Early in this part of the book (page 26) Salviati uses ideas equivalent to energy conservation on the inclined plane, and Sagredo readily agreed without demanding experimental proof. Then they segue to other topics. I think they return to it in a subsequent dialogue.