A metal block of mass $m$ is suspended from a rigid support through a metal wire of diameter $14 m m$. The tensile stress developed in the wire under equilibrium state is $7 \times 10^5 \mathrm{Nm}^{-2}$. The value of mass $m$ is $\_\_\_\_$ kg. (Take $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ and $\pi=\frac{22}{7}$ )