(a) A uniform bar of length \(L\), cross-sectional area \(A\), and unit mass \(ho\) is suspended vertically from one end. Show that its total elongation is \(\mathrm{d}\) \(=ho g \mathrm{~L}^{2} / 2 \mathrm{E}\).

(b) In the part (a), if the cross-sectional area, \(\mathrm{A}\) \(=300 \mathrm{~mm}^{2}\) and length \(=150 \mathrm{~m}\) and tensile load applied id \(20 \mathrm{kN}\) at the lower end, unit mass of the \(\mathrm{rod}=7850 \mathrm{~kg} / \mathrm{m}^{3}\) and \(\mathrm{E}=200 \mathrm{Gpa}\). Find the total elongation of the rod.