After the stress distribution within the object has been determined with respect to a coordinate system ( x , y ) , it may be necessary to calculate the components of the stress tensor at a particular material point P with respect to a rotated coordinate system ( x ′ , y ′ ) , i.e., the stresses acting on a plane with a different orientation passing through that point of interest —forming an angle with the coordinate system ( x , y ) (Figure 3). For example, it is of interest to find the maximum normal stress and maximum shear stress, as well as the orientation of the planes where they act upon. To achieve this, it is necessary to perform a tensor transformation under a rotation of the coordinate system. From the definition of tensor, the Cauchy stress tensor obeys the tensor transformation law. A graphical representation of this transformation law for the Cauchy stress tensor is the Mohr circle for stress.