A 3-m-long pin ended column of square hollow tube section is to be made of steel. Assuming E = 200 GPa, σₐₗₗ = 25 MPa, and using a factor of safety of 2.5 in computing Euler's critical load for buckling, determine the thickness of the tube if the column is to safely support a 100 kN load. Given: The outer dimension of the tube is 400 mm.
