The equation I posted is the solution to a differential equation that expresses the idea that a rate of change depends on the difference between two quantities

The equation I posted is the solution to a differential equation that expresses the idea that a rate of change depends on the difference between two quantities -- temperature, voltage and so forth. It is a very common solution in physics, describing the rate at which water moves between connected reservoirs, gas moves between connected tanks, current moves between connected circuits in electronics, and many other physical systems. More here: http://arachnoid.com/sage/differential1.html http://arachnoid.com/sage/differential1.html