A trapezoidal flat bar is suspended from above (the top of the bar is attached to the ceiling) and loaded just by its own weight. The bar thickness is constant, and its width varies linearly from bo...

A trapezoidal flat bar is suspended from above (the top of the bar is attached to the ceiling) and loaded just by its own weight. The bar thickness is constant, and its width varies linearly from bo at the bottom to 2bo at the top. The bar is made from a material that has a specific weight y. The bar's unstretched length is L, and its modulus of elasticity is E. Which of the following is the correct mathematical expression for the elongation of the bar?