U$3\mathrm{.}5200L{s}^{-1}$ of oil is pumped through a horizontal pipe made of heavily rusted steel. The pipe has an inner diameter of $0\mathrm{.}5m$ and a length of $1km.$ The oil has a density of $900kg{m}^{-3}$ and dynamic viscosity of $0\mathrm{.}01$ Pas at its mean temperature. How much mechanical energy dissipates per unit time due to friction?

Result: The loss of mechanical energy is $5\mathrm{.}03kW.$