Math 221 -- Assignment 2  (due Wednesday 2/25/98)

Find a differential equation (or system; ODE or PDE) that is relevant to
your major.  Write an explanation of it, directed at someone who knows
something about differential equations but nothing about your major.
Give reference(s).  Points will be awarded for good explanations and
"originality".  

By originality, I mean for example that I do not want a bunch of you
to turn in the same differential equation.  Also, do not use a differential
equation that is in the text for this course.  It is alright to use a
differential equation that you find in the text for another course.