where the growth rate r and the predation rate k are unspecified. Solutions of this
more general equation are very similar to those of Eq. (8). The equilibrium solution
of Eq. (9) is p(t) = k/r. Solutions above the equilibrium solution increase, while
those below it decrease.
You should keep in mind that both of the models discussed in this section have
their limitations. The model (5) of the falling object is valid only as long as theobject is falling freely, without encountering any obstacles. The population model
(8) eventually predicts negative numbers of mice (if p < 900) or enormously large
numbers (if p > 900). Both of these predictions are unrealistic,so this model becomes
unacceptable after a fairly short time interval.