An extruder has a barrel with an inside diameter of 30 mm. The screw has a channel depth of 3 mm, a channel width of 25 mm, and a flight angle of 16 degrees. The pumping section of the screw is 1.15 m long, and is used to extrude a flat polyethylene sheet. When melted, the polyethylene has a viscosity of 800 N-s/m2 . The die has a thickness of 0.5 mm, a width of 500 mm and is 25 mm long. In other words, the resulting sheet is 0.5 mm thick and 500 mm wide. The sheet comes out of the die at 150 mm/second. (a) Determine the rpm of barrel if the barrel rotates. (b) Determine the rpm of the screw, if the screw rotates. (c) Discuss the difference between (a) and (b), and its significance.