Explorations with Newton's Law of Cooling

The rate at which an object cools is proportional to the difference between its temperature and that of its environment. 
In this GeoGebra Worksheet you can adjust the initial temperature of the object (u0) and the constant temperature of the environment (T).
Also, you can indicate the temperature of the object (b) after the object has been cooling for (a) minutes.
Finally, observe that the ratio of the current rate of change of the temperature of the object to that of its original rate of change is equal to the ratio of the current difference between the temperature of the object and its environment and the original difference between the temperature of the object and its environment.