A crystalline grain of iron in a steel plate is situated in such a way that a tensile stress of 100 MPa (14.5 ksi) is applied along its [110] direction. a) What will be the resolved shear stress on the [11-1] direction within the {101) slip plane of this grain? b) What tensile stress will be required to produce a critical resolved shear stress of 31.1 MPa?