• # question_answer A solid shaft of diameter 'D' caries a twisting moment that develops maximum shear stress $\tau .$ If the shaft is replaced by a hollow one of outside diameter 'D' and  inside diameter D/2, then the maximum shear stress A) $1.067\,\tau$               B) $1.143\,\tau$         C) $1.333\,\tau$               D) $2\,\tau$

${{\tau }_{s}}=\frac{16T}{\pi {{D}^{3}}}$ ${{\tau }_{h}}=\frac{16T}{\pi {{D}^{2}}(1-{{k}^{4}})}=\frac{16T}{\pi {{D}^{3}}\left( 1-\frac{1}{16} \right)}=\frac{16}{15}{{\tau }_{s}}$ $=1.067\tau$