<prompt> Poiseuilles Hagen law isF PA-PB X 3.14 X r48nlF PAPB X 3.14 X r48nlF PAPB X 3.14 X r48nlF PA X PB X 3.14 X r48nl  <response>: Poiseuille-Hagen FormulaThe relation between the flow in a long narrow tube, the viscosity of the fluid, and the radius of the tube is expressed mathematically in the Poiseuille-Hagen formula:F PA-PB X dj8 X 1dj X r4LwhereF FlowPA-PB Pressure difference between the two ends of the tubedj Viscosityr Radius of tubeL Length of tube 