 Suppose one observes a quiescent black hole at a given moment, ignoring any possible quantum effects. As discussed above in  section 3.2,  there are three physical quantities of dynamical interest the black hole possesses that are, more or less, amenable to measurement, and that completely characterize the physical state of the black hole: its mass, its angular momentum, and its electric charge. These quantities, like those of systems in classical mechanics, stand in definite relation to each other as the black hole dynamically evolves, which is to say, they satisfy a set of equations characterizing their  behavior.[11] 