2. The frame of a drawing-office lamp contains a 300mm length of steel hollow section 10mm square (outside) with a wall thickness 1mm, on the end of which the lamp and shades are fixed. Gsteel = 78 kN/mm. (a) Calculate the torsional stiffness of the member. (10 marks) (b) Calculate the maximum stress which occurs when it is subjected simultaneously to a torque of 10 Nm and a bending moment of 10 Nm. (10 marks)