What does Pascal's law state regarding fluid pressure?

Pascal's law, also known as Pascal's principle, asserts that when a change in pressure is applied to an enclosed fluid, that change is transmitted undiminished to every point within the fluid. This means that if you apply pressure on one part of a fluid that is contained in a closed system, that pressure will be felt equally throughout the entire fluid. This principle is foundational in understanding how hydraulic systems operate, as it allows for the amplification of force through pressurized fluids, enabling machines like hydraulic lifts to function effectively.

The other options touch on different aspects of fluid behavior. While fluid pressure can indeed be influenced by changes in temperature, that relationship is not what Pascal’s law specifically addresses. The idea that fluid pressure can be increased by reducing the volume of a container relates more to principles of gas laws rather than Pascal's law. Lastly, while fluid pressure does act in all directions, the statement regarding an open tank is not a defining feature of Pascal's law, since the law specifically pertains to enclosed fluids.