Officer Aptitude Rating (OAR) Test 2025 – 400 Free Practice Questions to Pass the Exam

In fluid dynamics, particularly when discussing a cylinder and piston system, the key principle is that the volume of the oil remains constant when the fluid is incompressible, which is typically the case for liquids like oil. In a closed hydraulic system, as the piston moves, it displaces an equal volume of fluid within the cylinder. This means that any change in the position of the piston corresponds directly to the movement of fluid within the confines of the cylinder, while the total volume of fluid in the system does not change.

This principle is crucial because it governs the relationships between pressure, force, and area within hydraulic systems. By maintaining a constant volume, engineers can predict how changes in piston movement will affect the pressure exerted by the fluid throughout the system. This constancy allows for the reliable transfer of forces in applications such as hydraulic machinery and braking systems in vehicles.