Answer
(a) Students should plot $v$ on the vertical axis and $r^2$ on the horizontal axis.
(b) $n = \frac{2~g(\rho-\rho_f)}{(9)(slope)}$
Work Step by Step
$v = \frac{2r^2~g(\rho-\rho_f)}{9n}$
(a) To test this relationship. students should plot $v$ on the vertical axis and $r^2$ on the horizontal axis.
(b) When we plot $v$ on the vertical axis and $r^2$ on the horizontal axis, the slope of the line will be $\frac{2~g(\rho-\rho_f)}{9n}$
We can find an expression for $n$:
$slope = \frac{2~g(\rho-\rho_f)}{9n}$
$n = \frac{2~g(\rho-\rho_f)}{(9)(slope)}$
