A disk$-$shape particle is falling freely in a fluid. The density of the fluid is $2\mathrm{.}3$ kg$/$m$^3$ and the viscosity of the fluid is $1\mathrm{.}65\backslash$times $10^-5.$ The radius and the thickness of the particle is $580$m and $200$m respectively. The density of the particle is $1870$ kg$/$m$3.$ Determine the terminal velocity reached by the particle.