Question Figure below shows a hollow drill pipe for oil well. The pipe has an outer diameter of 80 mm, a wall thickness of 5 mm and a weight of 0.7 kN/m. The pipe is subjected to a torque and axial load as shown in figure. Determine: (a) The total stresses due to axial load and torque on at a point on its surface at section a and sketch the stress element. [10 marks] graph paper (b) By construct Mohr's circle, determine the following stress state at a point on its surface at section a. The principles stresses; The maximum-in-plane shearing stress; The orientation of principal plane (i) (ii) (iii) [15 marks] (c) Explain the usefulness of Mohr's Circle in material strength analysis and discuss at least ONE (1) of the application of Mohr's circle. Quote any references. [5 marks] 8 KN 1.8 kN.m 5 m 5 m