Equilibrium of a System in Physics

An energy diagram settles a whole motion at a glance. Plot the potential energy against position, draw one horizontal line for the constant total energy, and the difference between the two curves is the kinetic energy at that point. Where the line crosses the curve the body stops and turns back, and where the curve has a flat top or a dip the body is in equilibrium, stable if it sits in a dip and unstable if it balances on a crest. The blocks give that reading, the slope that gives the force, and the three tests that separate the kinds of equilibrium.