Which type of resistance in fluid power systems is due to the fluid's internal friction?

The correct response identifies friction resistance as the type of resistance in fluid power systems that arises from the internal friction of the fluid itself. This concept is essential in fluid mechanics, where the viscosity of the fluid plays a critical role in how it behaves under various pressures and flow conditions.

Friction resistance occurs as the fluid molecules interact with each other, creating resistance to flow due to their internal cohesion and the shear forces developed within the fluid as it moves. This internal friction is what gives rise to viscous losses in a system, making it a key factor in the efficiency of hydraulic and pneumatic systems. When the fluid flows over surfaces, the friction between the fluid and the surfaces also contributes to resistance, but the internal friction of the fluid is a fundamental characteristic inherent to its viscosity.

Local resistance often refers to resistance encountered at specific discontinuities or changes in the flow path, such as bends or restrictions, but it does not exclusively address the fluid’s internal properties. Pressure resistance is typically associated with the pressure drop due to flow through a system, which is influenced by many factors including friction but does not directly pertain to internal fluid characteristics. External resistance involves factors external to the fluid itself, such as drag on a moving object or the effects of surrounding media,