A cylindrical rod of length 1 m and radius 4 cm is mounted vertically. It is subjected to a shear force of 10^5 \mathrm{~N} at the top. Considering infinitesimally small displacement in the upper edge, the angular displacement \theta of the rod axis from its original position would be : (shear moduli, G=10^{10} \mathrm{~N} / \mathrm{m}^2 )