A stepped bar is clamped at both ends. A force of \(F=10,000 \mathrm{~N}\) is applied as shown in the figure. Areas of cross sections of the two portions of the bar are \(1 \times 10^{-4} \mathrm{~m}^{2}\) and \(2 \times 10^{-4}\) \(\mathrm{m}^{2}\), respectively. Young's modulus \(=10 \mathrm{GPa}\). Use three bar elements to solve the problem.

a. Sketch the displacement field \(u(x)\) as a function of \(x\) on an \(x y\) graph.

b. Calculate the stress at a distance of \(2.5 \mathrm{~m}\) from the left support.

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