A metal block of mass $m$ is suspended from a rigid support through a metal wire of diameter $14 \mathrm{mm}$. The tensile stress developed in the wire under equilibrium state is $7\times {10}^5 \mathrm{N} {\mathrm{m}}^{–2}$. The value of mass $m$ is ______ $\mathrm{kg}$.

(Take $g=9.8 \mathrm{m} {\mathrm{s}}^{-2}$ and $\pi =\frac{22}{7}$)