Newton's law of cooling says that the rate of cooling of an object is proportional to the difference between the temperature of the object and that of its surroundings (provided the difference is not too large). if t=t(t)t=t(t) represents the temperature of a (warm) object at time tt, aa represents the ambient (cool) temperature, and kk is a negative constant of proportionality, which equation(s) accurately characterize newton's law?