16 April 2007
Paul E. Hand
hand@cooper.edu
MA 401
Major Questions about Diffusions and Waves
Revised
Diffusions
What physical principles underlie diffusions?
How does diffusion smooth initial data?
What prole results from a point source?
Do diffusions
21 February 2007
Paul E. Hand
hand@cooper.edu
MA 401
Midterm
1. Consider a guitar string of length L, linear mass density , tension T , and ends held xed. Suppose the
string is pulled a slight distance and released.
(a) Draw the shape of the string before
9 February 2007
Paul E. Hand
hand@cooper.edu
MA 401
Problems for Midterm Makeup
The following problems are designed to reinforce concepts important to the midterm.
1. [Problem 1b] Some of you did not write down initial conditions for the velocity of the r
17 February 2007
Paul E. Hand
hand@cooper.edu
MA 401
Summary to date
Spatial derivatives of concentration induce diffusive ux.
If a diffusion is steady, the net ux into every region is zero.
For mathematical simplicity, we assume Ficks Law, that the relat