QUESTION 2 a) Figure Q2 shows a thick cylinder which is applied with external and internal pressures of P. and P, respectively. By using Lame's equations, prove that if P. = 0, the hoop stress at point A is given by: (3 marks) [0] r-r P Figure Q2 Po A. b) A close-ended thick cylinder is subjected to both internal and external pressures. The inner diameter of the cylinder is 150 mm and the outer diameter is 200 mm. If the tensile stress in the cylinder is limited to 20 MPa, and external pressure is 4 MPa, determine the internal pressure. Sketch also the radial stress, hoop stress and longitudinal stress distributions across the thickness of the cylinder. (7 marks)