IB Physics Higher Level (HL) Practice Exam

Bernoulli's principle describes the relationship between the speed of a fluid and its pressure. According to the principle, in a streamlined flow of an incompressible fluid, an increase in the fluid's speed is accompanied by a decrease in pressure. This can be understood through the conservation of energy – as fluid moves faster, there is less energy available for pressure.

In practical terms, when a fluid flows through a constriction, its speed increases, leading to a drop in pressure at that point. This principle is fundamental in various applications, such as in understanding lift in airplane wings and the behavior of gases and liquids in different environments.

The other options suggest different relationships that do not align with Bernoulli's principle, such as an increase in speed occurring with an increase in pressure or asserting that fluid flow has no effect on pressure, which contradicts the established understanding of fluid dynamics.