CDC Mobile Water Supply Practice Test – Full Exam Prep & Practice Questions

When fluid is forced through a restricted orifice, the cross-section area available for flow decreases, leading to an increase in velocity according to the principle of conservation of mass, known as the continuity equation. As the fluid speeds up, it experiences a drop in pressure due to the Bernoulli's principle, which states that in a flowing fluid, an increase in velocity occurs simultaneously with a decrease in pressure. This relationship illustrates how energy is transferred within the fluid: as some energy is converted into kinetic energy (hence the increase in velocity), the overall energy associated with pressure is reduced, resulting in lower pressure downstream of the orifice.

In contrast, the other options describe scenarios that do not align with these principles. For instance, pressure cannot simultaneously increase and velocity decrease under the conditions described, nor can both pressure and velocity decrease when fluid is forced through a restriction. Additionally, the idea that velocity remains constant contradicts the dynamics of fluid flow through a restricted area, which inherently leads to changes in flow velocity. Therefore, the chosen answer effectively captures the essential physics involved in fluid dynamics when navigating through an orifice.