A bar ABCD consists of three sections: AB is 25 mm square and 50 mm long, BC is of 20 mm diameter and 40 mm long and CD is of 12 mm diameter and 50 mm long.
a. Determine the stress set up in each section of the bar when it is subjected to an axial tensile load of 30 kN.
b. What will be the total extension of the bar under this load? For the bar material, E = 210GN/m2.