A cylindrical rod with diameter $2[$in$]$ and original length of $20[$ft$]$ is subjected to a tensile load of P $=1[$kip$].$ The rod is made from steel with E $=4,177,000[$ksf$]$ and a unit weight of $465[$lb$/$ft$3].($a$)$ Determine the displacement of the end of the rod from the tensile load only; $($b$)$ determine the displacement of the end of the rod from the weight only; and $($c$)$ determine the total displacement by summing the two displacements together. $($d$)$ Justify, using the principle of superposition, how you can determine the total displacement of an axially loaded member by calculating the displacements caused by each load separately and then summing them together.