According to Hagen Poiseuille's Equation, the pressure drop $\left(p_1-p_2\right)$ across a pipe of

Question

According to Hagen Poiseuille's Equation, the pressure drop $\left(p_1-p_2\right)$ across a pipe of length $\ell$ and uniform cross-section of diameter $d$ to maintain a liquid discharge $Q$ is given by (take $\eta=$ coefficient of dynamic viscosity)

Professor PC Thomas Classes · Answer

Hagen-Poiseulle's Equation
$
p_1=p_2=\frac{128 \eta Q \ell}{\pi d^4}=\frac{8 \eta Q \ell}{\pi r^4} 	ext { where } r=\frac{d}{2}
$