The viscosity of 5W-30 motor oil changes from 6.4 N ( s/m2 at −30 °C to 0.0090 N ( s/m2 at 100 °C. Model the oil circulation system of a car engine as a tube of radius 5.0 mm and length 2.1 m, driven by a pump that produces a pressure difference of 110 kPa across the ends of the tube.
(a) What volume flow rate does the pump produce when the oil is at −30 °C?
(b) What is the volume flow rate when the oil is at the operating temperature of 100 °C?