Problem $2($P$1\mathrm{.}12)$

For low$-$speed $($laminar$)$ steady flow through a circular pipe, as shown in the figure below, the velocity $u$

varies with radius and takes the form

$u(r)=B\frac{p}{}(r_o^2-r^2)$

where $$ is the fluid dynamic viscosity and $p$ is the pressure drop from entrance to exit.

What is the dimension of $p?$

What is the dimension of the constant $B?$