Problem attached. I would appreciate anyone's help. I am an alloy chemist working on an MS degree in materials engineering and have come to the mechanical engineering part of the program and am feeling a bit behind. Deriving an equation for this case is proving to be difficult for me although I believe we are still at the elementary mechanical review period. The basic situation is that of plane stress with an "important focus" on stiffness. The class is following the mechanical behavior of materials book by Dieter. I have a lot of time putting the pieces together but an now a bit stumped.