A finely ground mixture of galena and limestone in the proportion of $1$ to $4$ by mass is subjected to

an upward flowing stream of water at a velocity of $5m\frac{m}{s}.$ Assuming the size distribution of each

material is the same, estimate the percentage of galena in the material being carried away by the

upward stream and the percent in the material left behind. You can assume Stoke's Law applies.

Viscosity of water $1{10}^{-3}Pa.s$

${}_{\text{g}\text{a}\text{l}\text{e}\text{n}\text{a}}=7500k\frac{g}{m^3}$

${}_{limestone}=2700k\frac{g}{m^3}$

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