【Previous Video】 https://www.youtube.com/watch?v=7oGWsBh-Ofk What is a tensor? Why is the idea of a tensor necessary? Why do NOT people say an inertia matrix or a stress matrix? The kay is coordinate transformation. In this video, firstly, I explained a vector because it’s very important to understand what vectors are in order to understand rank-2 tensors. Secondly, I gave the definition of rank-2 tensors by explaining an inertia tensor and a stress tensor. After that, I gave an example of a matrix that is NOT a tensor to understand what rank-2 tensors are. Finally, I gave a way how to know whether a matrix is a tensor or not. My twitter https://twitter.com/6MitsuAsai