Pitot tube application — the primary quantity measured using a Pitot tube is:

Introduction / Context:
A Pitot tube is a widely used instrument for measuring fluid speed in pipes, ducts, and open flows. It senses stagnation (total) pressure at its tip and compares it with static pressure to infer velocity from Bernoulli’s principle.

Given Data / Assumptions:

• Incompressible flow at moderate speeds.
• Total (stagnation) and static pressures can be measured.
• Bernoulli relation between points on the same streamline applies (with correction factors if needed).

Concept / Approach:

The Pitot tube provides the dynamic pressure q = p_total − p_static. For incompressible flow, v = sqrt(2 * q / rho). Thus, while it senses a pressure difference, the device is used specifically to determine flow velocity.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Calibration with a known flow (e.g., venturi or laminar flow standard) validates the velocity reading and correction factors (Pitot coefficient close to 1).

Why Other Options Are Wrong:

“Pressure” alone is ambiguous; “difference in pressure” is an intermediate measurement, but the asked primary application is velocity determination; “none” is incorrect.

Common Pitfalls (misconceptions, mistakes):

Ignoring alignment with flow direction; neglecting density corrections or compressibility at high Mach numbers.

Final Answer:

velocity of flow