Problem 2: (15 pts) A brittle material has the properties Sut -210 MPa and Suc- 630 MPa. Using the brittle Coulomb-Mohr and modified-Mohr theories, determine the factor of safety for the

following states of plane stress. (a) o 175 MPa, o,-105 MPa [5 pts] (b) a=140 MPa, Try=-70 MPa [5 pts] (c) = -105 MPa, o, 70 MPa, ty=-105 MPa [5 pts]