At a point in an elastic material, a direct tensile stress of 60 N/mm and a direct compressive stress of 40 N/mm are applied on planes at right angles to each other. The maximum principal stress is limited to 75 N/mm (tensile) 11. The shear stress that may be allowed on the planes, where the above stresses are acting, (b) 41.53 N/mm (d) 75 N/mm (a) 21.32 N/mm (c) 63.75 N/mm 12. The minimum principal stress (in N/mm) is (a) 45 (comp) (c) 45 (tension) (b) 55 (comp) (d) 55 (tension) 13. The maximum shear stress (in N/mm) is (a) 37.5 (b) 65 (c) 60 (d) 50