The flow rate of a liquid is ______.

The flow rate of a liquid is ______.

• A. Fluid Viscosity
• B. Temperature
• C. Pressure Gradient
• D. Tube Length

Answer: (C)

Flow rate is driven by the pressure gradient—the difference in pressure between two points pushing the liquid from high to low pressure. If you increase this pressure difference while keeping the fluid and the tube the same, more fluid flows per unit time. Viscosity, tube length, and radius influence how easily the liquid moves (they determine the resistance to flow), so they shape the actual rate, but without a pressure gradient there isn’t a net flow. In many tube-flow relationships, flow rate is proportional to ΔP and inversely related to resistance, which grows with viscosity and length and shrinks with radius.

Flow rate is driven by the pressure gradient—the difference in pressure between two points pushing the liquid from high to low pressure. If you increase this pressure difference while keeping the fluid and the tube the same, more fluid flows per unit time. Viscosity, tube length, and radius influence how easily the liquid moves (they determine the resistance to flow), so they shape the actual rate, but without a pressure gradient there isn’t a net flow. In many tube-flow relationships, flow rate is proportional to ΔP and inversely related to resistance, which grows with viscosity and length and shrinks with radius.