Which branch of applied mechanics deals with the physical characteristics exhibited by fluids at rest and in motion?

• A. Pneumatics
• B. Fluid Dynamics
• C. Hydraulics
• D. Thermodynamics

Answer: (C)

Liquids behave under pressure whether they’re standing still or flowing, and hydraulics is the branch that addresses these behaviors in engineering systems. It covers how liquids transmit forces, how pressure relates to height, and how pumps, pipes, and valves influence movement. In a static state, you analyze pressure distribution in a still liquid; in motion, you focus on flow rates, head losses, and pump performance. Pneumatics involves gases, thermodynamics deals with energy and heat transfers, and fluid dynamics centers on liquids in motion more narrowly. Hydraulics best fits the idea of studying the physical characteristics of fluids both at rest and in motion.