The traction's on the planes that intersect at the origin of Figure 11 can be subdivided into perpendicular and parallel components for each plane. The component perpendicular to the plane is termed normal stress (sn) and the component parallel to the plane is termed shear stress (t). Figure 13 illustrates the relationship between the traction, s, and the normal (sn) and shear stress (t) components for a single plane.