$1.\backslash ($ A $\backslash )$ bar $\backslash ($ A B C D $\backslash )$ has a circular cross$-$section of $75$ mm diameter over half its length and $50$ mm diameter over the remaining half of its length. A torque of $1$ KNm is applied at C midway between $\backslash ($ B $\backslash )$ and $\backslash ($ D $\backslash )$ as shown in figure below. Sketch the distribution of torque along the length of the bar and calculate the maximum shear stress and the maximum angle of twist in the bar. Take G $\backslash (=70000\backslash$mathrm$\{$~N$\}/\backslash$mathrm$\{$mm$\}^\{2\}\backslash )$