Solid particles of diameter $0.1 \mathrm{~mm}$ and density $2 \mathrm{~g} / \mathrm{cm}^{3}$ are to be separated from air in a horizontal settling chamber. If the air flow rate is $100 \mathrm{ft}^{3} / \mathrm{s}$ and the maximum height of the chamber is $4 \mathrm{ft}$, what should the minimum length and width be for all of the particles to hit the bottom before exiting the chamber? (Air: $ho=0.075 \mathrm{lb}_{\mathrm{m}} / \mathrm{ft}^{3}, \mu=0.018 \mathrm{cP}$ ).