In fluid systems, flow direction is driven by the gradient between which two states?

• A. No pressure gradient
• B. Low to high pressure
• C. High to low pressure
• D. Equal pressure

Answer: (C)

Flow in fluid systems follows a pressure gradient. Pressure acts as a potential energy per unit volume, and the net force on a fluid element points from regions of higher pressure toward regions of lower pressure. As a result, fluids naturally move from high pressure to low pressure, converting pressure potential into kinetic energy while overcoming friction along the path. If there’s no pressure difference, there’s no spontaneous flow; moving from low to high pressure would require external work, such as a pump. Equal pressure provides no driving force, so no net flow occurs.