Why do we use energy conservation forto obtain maximum displacement of the block in spring block system whereas for displacement from equilibriumof the mean position(equilibrium position) we use net force$F_{net} = 0$ on the block?
Post Closed as "Not suitable for this site" by Lelouch, John Rennie, Charles Francis, Jon Custer, Michael Seifert
completely changed the question since the O.P was new