(USCS units) An extruder barrel has a diameter = 4.5 in and its L/D ratio= 22. The screw channel depth = 0.25 in, and its pitch = 4.8 in. It rotates at 60 rev/min. Viscosity of the polymer melt isS0(10) Ib-sec/in'. What head pressure is required to obtain a volume flow rate = 175 in'/min?

Fig: 1