Consider a bar element as shown in the figure. The cross-sectional areas are A1 and A2 at nodes 1 and 2, respectively, and vary linearly.
In addition, the gravitational acceleration is applied along the axial direction of the bar, such that the distributed load per unit length is f(x) = ρgA(x), where ρ is the density and g is the gravitational acceleration. Construct the discrete variation equation for the element.
