Passage V

Viscous fluid flow occurs when various parts of a fluid interact with each other to produce forces that inhibit flow and generate heat. Students performed 3 studies of viscous fluid flow using the experimental setup shown in Figure 1 below.

In each trial of the studies, the students sent a fluid through a tube such that the fluid completely filled the tube. The fluid had a viscosity η; the tube had a radius R and was fitted with 2 pressure gauges, Gauge G and Gauge H, that were a distance D apart. The pressure of the fluid at Gauge G minus the pressure of the fluid at Gauge H always equaled 5 kilopascals. (A kilopascal, kPa, is a unit of pressure, which is defined as force per unit area.) Using a flow meter, the students measured the fluid’s flow rate through the tube, F, in milliliters per second (mL/sec).

Study 1

The students measured F for various fluids, each having a different η, that flowed, one at a time, through a tube having an R of 5.00 mm and a D of 1.00 m (see Table 1).

Study 2

The students measured F for a fluid having an η of 1.0 × 10⁻³ Pa·sec that flowed through each of various tubes having the same D, 1.00 m, but different R (see Table 2).

Study 3

The students measured F for a fluid having an η of 1.0 × 10⁻³ Pa·sec that flowed through each of various tubes having the same R, 5.00 mm, but different D (see Table 3).