I already checked, however the book I want is for analytical mechanics, specifically those problems dealing Lagrange mechanics and the principle of virtual work.
Anyway thank you very much!
I'm looking for a book of classical mechanics. I do not remember the title or the author, but has pictures of this kind, if someone could help me find it would be greatly appreciated.
https://dl.dropboxusercontent.com/u/61701794/Captura%20de%20pantalla%20de%202016-09-10%2014-56-03.png...