A single crystal of zinc is oriented for a tensile test such thatits slip plane normal makes an angle of 66.0° with the tensileaxis. Three possible slip directions make angles of 30°,48°, and 78° with the same tensile axis.
(a) Which of these three slip directions is mostfavored?
(b) If plastic deformation begins at a tensilestress of 2.56 MPa (371.3 psi), determine the critical resolvedshear stress for zinc.