According to Pascal's Law, pressure in a confined fluid is equal and acts __________.

• A. Tangential to walls
• B. Perpendicular to all surfaces
• C. Parallel to gravity
• D. Along the surface

Answer: (B)

Pressure in a confined fluid is transmitted equally in all directions and acts normal to any surface it contacts. This means the force due to pressure on a surface points perpendicular to that surface, not along it. The isotropic nature of pressure lets hydraulic systems transfer a force from a small-area piston to a larger-area piston because the same pressure acts on both, with the resulting force proportional to each surface’s area. Gravity can cause pressure to vary with depth, but the direction of the pressure force on a surface remains perpendicular to that surface. So the statement that best describes Pascal’s Law is that pressure acts perpendicular to all surfaces.