(b) A thin-walled hollow circular tube is subjected to an axial tensile force, which produces normal stress 10 MPa on any cross-section (see Figure Q1). It is also subjected to a torque, which produces shear stress of 20 MPa, as shown. Sketch the Mohr's circle for any element of the tube, and hence calculate the magnitudes of the principal stress and the maximum shear stress. Calculate axial force, assuming that the inner radius of the circular hollow section is 20 cm and outer radius is 21 cm. [10] = 10MPa T = 20MPa Figure Q1