Pitot Tube — What Quantity Does It Measure? In fluid mechanics practice, a Pitot tube inserted into a flow is primarily used to determine which hydraulic quantity at a specific point in a pipe or channel?

Introduction:
A Pitot tube is a classic point-velocity probe that converts local kinetic energy into a measurable pressure rise by stagnating the flow at its tip. It is widely used in hydraulic laboratories, HVAC ducts, rivers, and aircraft airspeed systems to estimate local velocity from measured pressures.

Given Data / Assumptions:

• Incompressible liquid flow (water) or low-speed gas flow.
• Steady conditions near the measurement point.
• Access to both stagnation (impact) pressure and static pressure, often via a Pitot-static arrangement and a manometer or pressure transducer.

Concept / Approach:
Bernoulli's relation along a streamline between a point in the flow and the stagnation point gives V from the difference between stagnation and static pressures. The key formula is V = sqrt(2 * Delta p / rho) after applying an empirical coefficient if needed.

Step-by-Step Solution:
Measure stagnation pressure p_0 at the Pitot opening facing the flow.Measure static pressure p_s (via side ports or a separate tap).Compute Delta p = p_0 - p_s.Find local speed: V = C * sqrt(2 * Delta p / rho), where C is a calibration coefficient near 1.0.

Verification / Alternative check:
Traverse the Pitot across the cross-section to build a velocity profile; integrating yields discharge, confirming that the device itself measures point velocity, not total flow directly.

Why Other Options Are Wrong:
Pressure difference between two arbitrary points requires a differential tap, not a Pitot alone. Total pressure in a pipe is a derived term, but the Pitot measures the stagnation pressure at one point. Discharge needs area integration or another primary device (weir, Venturi meter).

Common Pitfalls:
Misaligning the Pitot with flow direction; ignoring turbulence-induced fluctuations; using the formula without fluid density or calibration factor.

Final Answer:
velocity of flow at the required point in a pipe