Question $4[25$ marks$]$

Glycerin at $25C$ flows through a straight hydraulic copper tube, $80mm$ OD with a $2\mathrm{.}8mm$ wall, at a flow rate of $180\frac{L}{m}in.$ Compute the pressure difference between two points $25\mathrm{.}8m$ apart if the first point is $0\mathrm{.}68m$ below the second point.