Answer
0.47 m/s
Work Step by Step
Let's apply the equation $Re=\frac{2v\rho R}{\eta}$ to find the average speed.
$Re=\frac{2v\rho R}{\eta}=>v=\frac{(Re)\eta }{2\rho R}$ ; Let's plug known values into this equation.
Average speed = v= $\frac{2000(4\times10^{-3}Pa\space s)}{2(1060\space kg/m^{3})(8\times10^{-3}m)}=0.47\space m/s$
