Recall from Example 3.1 and the subsequent discussion that there are at least two "types" of stress: the true (Cauchy) stress, which is a measure of forces acting over a deformed oriented area A, and the nominal (PiolaKirchhoff) stress, which is a measure of forces acting over the undeformed oriented area Ao. Note, too, that the chordae, like many soft tissues, often conserves its volume when deforming (i.e., it behaves incompressibly, which because of the large strains cannot be accounted for via v=21 ). If the original length is L and the current length is l, volume conservation requires LAo=IAA=Ao(L/l) assuming uniform stress and strain. Hence, xx=Af=Aof(Ll)=xx, where =l/L is a stretch ratio and xx is the nominal stress. If L=10mm, compare the values of xx and xx for all / from 10.001 to 10.7mm