Describe the plot of pressure versus flow rate.

Describe the plot of pressure versus flow rate.

• A. It was exponential; flow rate rose faster than pressure.
• B. It was constant; flow rate did not change with pressure.
• C. It was linear, and the flow rate increased with increased pressure.
• D. It was inverse; flow rate decreased as pressure increased.

Answer: (C)

In a simple fluid-resistor model, the flow rate is directly proportional to the driving pressure difference. This is written as Q = ΔP / R, so rearranging gives P = R Q. That means the plot of pressure versus flow rate is a straight line through the origin, with slope equal to the resistance. As pressure increases, flow increases in direct proportion. The other shapes would require changing resistance or more complex vessel behavior, but with constant resistance the relationship is linear and flow rises as pressure rises.

In a simple fluid-resistor model, the flow rate is directly proportional to the driving pressure difference. This is written as Q = ΔP / R, so rearranging gives P = R Q. That means the plot of pressure versus flow rate is a straight line through the origin, with slope equal to the resistance. As pressure increases, flow increases in direct proportion. The other shapes would require changing resistance or more complex vessel behavior, but with constant resistance the relationship is linear and flow rises as pressure rises.