For the plane truss shown below:

$($a$)$ Tabulate all the member forces and reactions due to the individual unit vertical nodal loads applied to joints $2,3,$ and $4($force influence table$).$ Use the GTSTUDL output file.

$($b$)$ Use the force influence table in part $($a$)$ to draw the influence line for member $(4)($c$)$ Determine the following for P$,=$P$,=6$ kip, P$=10$ kip and P$,=$P$,=12$ kip $($i$)$ The force for member $(4).($ii$)$ The vertical displacement at joint $7.($iii$)$ The horizontal displacement at joint $5.$ u $=($iv$)$ The vertical reaction at joint $1.$ R