Calculate the largest particle diameter as a function of particle density ${}_p$ for gravity settling in the Stokes' law regime for settling in water and settling in air at ambient conditions. Assume that the particles are spherical and that Stokes' law holds for $R{e}_{p}0\mathrm{.}3.($Note: for air $($density $1\mathrm{.}2k\frac{g}{m^3}$ and viscosity $1$:$84**{10}^{-5}Pa.s)$ and for water $($density $1000k\frac{g}{m^3}$ and viscosity $0\mathrm{.}001Pa.s).$