1) The document discusses natural coordinates for a 1D bar element in finite element analysis. 2) It defines the natural coordinates (L1, L2) of any point P on the bar element in terms of the Cartesian coordinates (x1, x2) of the two nodes and the length L of the element. 3) The natural coordinates at node 1 are derived to be (1, 0) and at node 2 to be (0, 1).