Which phrase best describes the flow of energy in a fluid system?

• A. Energy to Push a Fluid
• B. Energy of Motion
• C. Based on Position
• D. Energy Stored in a System

Answer: (A)

In a fluid system, energy flow is best described by the work done to move the fluid. When energy is applied—by a pump, pressure difference, or other forcing—it pushes the fluid, overcoming resistance and driving flow. This input of energy to push the fluid is what establishes and sustains movement, so the phrase that captures the flow of energy most directly is "Energy to Push a Fluid."

While energy present in moving fluid exists as kinetic energy and energy associated with position (potential energy), those describe the state of the fluid rather than how energy is entering and driving the flow. "Energy to Push a Fluid" specifically highlights the active input that causes and maintains flow, which is why it is the best choice.