What happens to the pressure in a hydraulic system when the volume decreases?

In a hydraulic system, when the volume decreases while the amount of fluid remains constant, the pressure increases. This relationship is explained by Pascal's principle, which states that when pressure is applied to a confined fluid, it is transmitted undiminished in all directions.

When the volume of the fluid is reduced – for instance, by closing a valve – the same amount of fluid now occupies a smaller space. According to the ideal gas law (when considering compressible fluids) and hydraulic principles (for incompressible fluids), reducing the volume will lead to an increase in pressure because the molecules of fluid are pushed closer together, increasing their activity and, consequently, the pressure.

This principle is foundational in understanding hydraulic systems, as it allows for the transmission of force through pressurized liquids. Thus, in situations where the volume decreases, the result is a corresponding increase in pressure.