A mild steel bar of square cross-section has a sectional area 200 mm2. It is subjected to an axial force of 20 kN as shown in the below figure. The intensity of the normal tensile stress in N/mm2 on the oblique plane 1-1 at 45° with the YY-axis which is normal to the longitudinal axis will be
A=200mm2
σ1=PA=20×1000200Nmm2=100N/mm2
θ=45∘
σn=(σ1+02)+(σ1+02)cos2θ
=1002+1002cos90∘=50N/mm2