According to Bernoulli's principle, as a fluid flows through a narrow passage or stricture, which of the following will occur? 1. Fluid velocity will decrease. 2. Lateral pressure will fall. 3. Total energy will increase

a. 2 and 3 only
b. 1 and 2 only
c. 1 and 3 only
d. 2 only

ANS: D
When a fluid flows through a tube of uniform diameter, pressure decreases progressively over the tube length. When the fluid passes through a constriction, the pressure drop is much greater. This large pressure drop can be observed in the fourth water column in Figure 6-24. The eight-eenth-century scientist Daniel Bernoulli was the first to carefully study this effect, which now bears his name. According to the law of continuity, as the fluid moves into the narrow or con-stricted portion of the tube, its velocity must increase (vb > va). According to the Bernoulli's the-orem, the higher velocity at point b should result in a lower lateral pressure at that point (Pb < Pa). Thus, as a fluid flows through the constriction, its velocity increases and its lateral pressure de-creases.