Pressure in a system builds up only when there is what to flow?

Pressure in a system builds up only when there is what to flow?

• A. Volume
• B. Viscosity
• C. Resistance
• D. Temperature

Answer: (C)

Pressure builds up when there is something to push the fluid through—a resistance to flow. The pump or driving force creates a tendency for flow, but if the path offers resistance (narrow passages, restrictions, fittings, valves), the fluid must push harder, and upstream pressure rises to overcome that resistance. This relationship is like ΔP = Q × R: for a given flow rate, higher resistance requires higher pressure; with little or no resistance, the pressure rise is small. Volume simply changes how much fluid is present, and temperature can influence how easily the fluid flows (via viscosity), but the direct reason pressure increases is the presence of resistance to flow.

Pressure builds up when there is something to push the fluid through—a resistance to flow. The pump or driving force creates a tendency for flow, but if the path offers resistance (narrow passages, restrictions, fittings, valves), the fluid must push harder, and upstream pressure rises to overcome that resistance. This relationship is like ΔP = Q × R: for a given flow rate, higher resistance requires higher pressure; with little or no resistance, the pressure rise is small. Volume simply changes how much fluid is present, and temperature can influence how easily the fluid flows (via viscosity), but the direct reason pressure increases is the presence of resistance to flow.