$($a$)$ What do you mean by statically indeterminate force system? A rigid bar AB is supported by three rods as shown in the figure. The central rod is copper rod and has a cross$-$sectional area of $103m{m}^2.$ The two outer rods are made up of steel and each having cross$-$sectional area of $250m{m}^2.$ All rods are $2$ metres long, The three rods are equally spaced and loads of $50$ kN each are applied midway between the rods. Neglecting the weight of the bar $AB,$ determine the force in each of the vertical rods. Assume that the bar remains horizontal after the loads have been applied. Take for steel $E=200$GPa and for copper $E=120$GPa.