Hệ thức Stokes:

\(V = \frac{{2{r^2}g}}{{\left( {{d_1} - {d_2}} \right)9\eta }}\)

\(V = \frac{{\left( {{d_1} - {d_2}} \right)g}}{{2{r^2}9\eta }}\)

\(V = \frac{{2{r^2}\left( {{d_1} - {d_2}} \right)}}{{gx9\eta }}\)

\(V = \frac{{2{r^2}\left( {{d_1} - {d_2}} \right)g}}{{9\eta }}\)