This document discusses the elongation of a uniformly tapering circular rod under an axial tensile load. It defines the geometry of the rod, including the larger diameter D1, smaller diameter D2, and total length L. It then derives equations for the diameter Dx, cross-sectional area Ax, stress σx, strain εx, incremental change in length δlx, and total elongation δl of the rod. As an example, it calculates the modulus of elasticity E of a rod with given D1, D2, L, load P, and elongation. The key results are that the diameter varies linearly with distance x from D1, and the total elongation is given by δl = 4PL/(πE