How is a differential equation different from a regular one? Well, the solution is a function (or a class of functions), not a number. How do you like me now (that is what the differential equation would say in response to your shock)!
Most differential equations cannot be solved by "hand" (through analytical means). However, this doesn't mean that we have to give up! As we'll see in this tutorial, we can use numerical methods to approximate a solution to a differential equation. In particular, we'll learn about Euler's Method which is a fairly intuitive way to do this!
In this equations, all of the fat is fully mixed in so it doesn't collect at the top. No (that would be homogenized equations).
Actually, the term "homogeneous" is way overused in differential equations. In this tutorial, we'll look at equations of the form y'=(F(y/x)).