$Q1u=u_{\text{m}\text{a}\text{x}}[1-(\frac{r}{r_0}{)}^2],$

where $u_{\text{m}\text{a}\text{x}}is$ the maximum velocity $on$ the axis $of$ the pipe, $r_{0}is$ the radius $of$ the pipe, and

$ris$ the distance between the point and the axis. Determine the average velocity $of$ the

cross section.