The column is subjected to an axial force of 8 kN, which is applied through the centroid of the cross-sectional area. Determine the average normal stress acting at section a-a. Show this distribution of stress acting over the area’s cross section.

Please help me with this question.

A high-strength steel [E = 188 GPa] tube having an outside diameter of 67 mm and a wall thickness of 4.1 mm is bent into a circular curve having a 42-m radius of curvature. Determine the maximum magnitude of the bending stress max developed in the tube. Answer: Omax = i MPa.