1. What is Mach Number?

The Mach number is a dimensionless quantity 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 is Mach Number Calculated?

The calculator uses these equations:

Where:

• \( M \) — Mach number (dimensionless)
• \( v \) — Velocity of the object (m/s)
• \( a \) — Speed of sound in the medium (m/s)
• \( \gamma \) — Heat capacity ratio (specific heat ratio)
• \( R \) — Specific gas constant (J/(kg·K))
• \( T \) — Absolute temperature (K)

Explanation: The Mach number compares an object's speed to how fast sound travels in the surrounding medium.

3. Importance of Mach Number

Details: Mach number is crucial in aerodynamics. Different flight regimes are classified by Mach number:

• Subsonic: M < 0.8
• Transonic: 0.8 ≤ M ≤ 1.2
• Supersonic: 1.2 < M < 5
• Hypersonic: M ≥ 5

4. Using the Calculator

Tips: Enter velocity in m/s, heat capacity ratio (1.4 for air), gas constant (287 J/(kg·K) for air), and temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What's the speed of sound at sea level?
A: Approximately 343 m/s (1,235 km/h) in air at 20°C (293.15 K).

Q2: Why does Mach number matter in aviation?
A: Different aerodynamic effects occur at different Mach regimes, affecting aircraft performance and control.

Q3: How does temperature affect Mach number?
A: Higher temperatures increase the speed of sound, decreasing Mach number for a given velocity.

Q4: What's a typical γ value for air?
A: For dry air at standard conditions, γ ≈ 1.4.

Q5: Can Mach number be less than 1?
A: Yes, Mach < 1 is subsonic, which is typical for most commercial aircraft.