Pascal's law states what principle in hydraulic systems?

• A. Pressure in a fluid only acts in the vertical direction.
• B. Pressure applied to a confined fluid is transmitted uniformly in all directions, acting on all surfaces.
• C. Pressure remains constant regardless of acceleration.
• D. Pressure is inversely proportional to volume.

Answer: (B)

The main idea is that in a confined fluid, pressure is transmitted equally in all directions. This is Pascal’s law: when you apply pressure to a contained fluid, that pressure is conveyed undiminished throughout the fluid and to the walls of the container. In a hydraulic system, this means the pressure you create on one piston shows up everywhere in the fluid, so it acts on all surfaces, including other pistons. Because pressure is the same everywhere, you can multiply force by using pistons of different sizes: the same pressure times a larger piston gives a larger force (F = P × A). This is why hydraulic devices can lift heavy loads with relatively small input forces. The other statements don’t fit because pressure does not act only vertically, pressure isn’t constant regardless of acceleration, and pressure is not generally inversely proportional to volume (that’s a different gas law).