7. A pin-ended column of height 2.0m has a circular cross-section of dimeter 60mm, wall thickness 2.0 mm and is converted to an open section by a narrow longitudinal slit; the ends of the column are free to wrap. If the column is made from materials with E-50 Gpa and G-15Gpa, determine the values of axial load which would cause the column to buckle in: a) Pure bending mode. b) Pure torsion mode