In this video, the study of constitutive relations is continued. Briefly, what has been covered in the previous course is discussed. Frame Invariance or Invariance with respect to the observer is discussed in this video. It is an exceedingly important concept in the field of nonlinear elasticity. Physically it is easy to understand but the mathematical expression may be abstract.
The discussion on invariance with respect to the observer continues in this video. Effect of change of basis is shown for a rigid body which is the same as a rigid body experiencing translation and rotation. The tensor invariant is shown. Effect of change of basis for scalars is discussed.