Q1 [Total 4 marks] For the plane-stress condition given below: Ox = 400 MPa Oy = 500 MPa Txy = - 30 MPa Construct a Mohr's circle of stress, find: (a)

the principal stresses and the orientation of the principal axes relative to the x,y axes [1 mark]; (b) determine the stresses on an element, rotated in the x-y plane 60° counter- clockwise from its original position [1 mark]; Show these stresses on a sketch of an element oriented at this angle [1 mark]; (c) Also, using the matrix transformation law to compare the solutions with Mohr's circle [1 mark].