1. What is Mach Number?

The Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. It's commonly used in aerodynamics to characterize high-speed flight.

2. How Does the Calculator Work?

The calculator uses the Mach number formula:

Where:

• \( M \) — Mach number (dimensionless)
• \( v \) — Velocity of the object (m/s)
• \( a \) — Speed of sound in the medium (m/s)

Explanation: The Mach number indicates how fast an object is moving relative to the speed of sound in the surrounding medium.

3. Importance of Mach Number

Details: Mach number is crucial in aerodynamics for classifying flight regimes (subsonic, transonic, supersonic, hypersonic) and predicting compressibility effects.

4. Using the Calculator

Tips: Enter velocity in meters per second and speed of sound in the medium (default is 343 m/s for air at 20°C). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the speed of sound in air?
A: Approximately 343 m/s at 20°C (68°F) at sea level. It varies with temperature (about 0.6 m/s per °C).

Q2: What are different Mach regimes?
A: Subsonic (M < 0.8), Transonic (0.8 < M < 1.2), Supersonic (1.2 < M < 5), Hypersonic (M > 5).

Q3: Why is Mach 1 significant?
A: Mach 1 represents the speed of sound. Crossing this threshold creates a sonic boom and significant changes in aerodynamic behavior.

Q4: Does Mach number depend on altitude?
A: Indirectly - as temperature decreases with altitude, so does the speed of sound, affecting the Mach number for a given airspeed.

Q5: What's the difference between indicated and true Mach number?
A: Indicated Mach number is what instruments show, while true Mach number accounts for instrument errors and actual atmospheric conditions.