In section 1.3 we saw that the autonomous differential equation m dv dt = mg − kv, where k is a positive constant and g is the acceleration due to gravity, is a model for the velocity v of a body of mass m that is falling under the influence of gravity. because the term −kv represents air resistance, the velocity of a body falling from a great height does not increase without bound as time t increases. use a phase portrait of the differential equation to find the limiting, or terminal, velocity of the body. lim v(t -> infinity)=