

How Does a Pitot Tube Measure Fluid Flow Velocity?
The topic of Pitot tube is important in physics and helps us understand various natural phenomena, instruments, and physical laws. From measuring the speed of airplanes to analysing fluid flow in engineering, Pittot tubes provide real-time, accurate results that are crucial in both scientific study and technology.
Understanding Pitot Tube
Pitot tube refers to a simple instrument used to measure the velocity of fluid flow, most commonly air. It plays a vital role in topics like fluid mechanics, Bernoulli’s principle, and pressure measurement. The device consists typically of a straight tube pointing directly into the fluid stream; it measures the pressure as the fluid stagnates at the tube's opening.
Formula or Working Principle of Pitot Tube
The concept is often explained using Bernoulli's principle. The formula for measuring the fluid velocity (v) using a Pitot tube is:
v = √[2(Pt - Ps)/ρ]
where Pt is the stagnation (total) pressure, Ps is the static pressure, and ρ (rho) is the density of the fluid. The Pitot tube collects both static and stagnation pressure and uses their difference to calculate the fluid's velocity.
Here’s a useful table to understand Pitot tube better:
Pitot Tube Table
Concept | Description | Example |
---|---|---|
Stagnation Pressure | Pressure measured by the Pitot tube in flow direction | Air hitting aircraft probe |
Static Pressure | Pressure of fluid at rest or moving parallel to probe | Cabin air pressure in airplane |
Velocity Measurement | Calculated from the difference in stagnation and static pressure | Aircraft airspeed indication |
Worked Example / Practical Experiment
Let’s solve a problem or understand an experiment step by step:
1. Identify the known values: Pt = 105 kPa, Ps = 100 kPa, ρ = 1.2 kg/m³
2. Apply the correct formula: v = √[2(Pt - Ps)/ρ]
3. Solve the equation: v = √[2(5000)/1.2] ≈ 91 m/s
4. Analyze the physical meaning of the result: The measured airspeed (velocity) is about 91 meters per second.
Conclusion: This approach helps apply Pitot tube concepts in real-life aviation or engineering systems.
Practice Questions
- Define Pitot tube with an example.
- What formula is used in Pitot tube calculations?
- How does Pitot tube affect real-world systems such as aircraft?
- Write the working principle behind Pitot tube measurement.
Common Mistakes to Avoid
- Misinterpreting the unit or formula for Pitot tube calculations.
- Confusing static and stagnation pressure readings, leading to errors.
- Neglecting the fluid density (ρ) factor in calculations.
Real-World Applications
Pitot tube is widely used in fields like aviation (to measure aircraft airspeed), weather stations, automobile testing (race cars), and fluid mechanics laboratories. It helps ensure safety and performance in aerospace and engineering. Vedantu helps you connect such concepts with real-world physics applications and exam problems.
In this article, we explored Pitot tube — its meaning, formula, practical relevance, and usage in physics. Keep exploring such topics with Vedantu to improve your understanding. For more details on fluid flow, check the fluid mechanics or Bernoulli’s principle topic pages.
FAQs on Pitot Tube - Definition, Diagram & Uses in Physics
1. What is a Pitot tube and how does it work?
2. What is the Pitot tube equation, and how is it derived?
3. How is a Pitot tube used to measure airspeed in airplanes?
4. What are the common applications of a Pitot tube?
5. What are the different types of Pitot tubes?
6. What are the potential errors and blockages associated with Pitot tubes?
7. How do I draw and label a Pitot tube diagram?
8. What is the difference between static pressure and stagnation pressure?
9. Why are Pitot tubes important in aviation?
10. How can I solve numerical problems related to Pitot tubes?
11. What is the significance of Bernoulli's principle in Pitot tube operation?
12. How do I interpret the results from a Pitot tube measurement?

















