Question

Please arrange the following according to escalating Mach number.
A. Supersonic
B. Transonic
C. Hypersonic
D. Subsonic
Choose the correct answer from the options given below:

• A. D, B, A, C
• B. C, B, A, D
• C. A, D, C, B
• D. B, A, D, C

Hint:

The word "Sonic" refers to the speed of sound ($M=1$). "Sub-" means below, "Trans-" means across/around, "Super-" means above, and "Hyper-" means far beyond.

Answer 1

The Correct Option is A

Concept: The Mach number (M) is defined as the ratio of local flow velocity to the local speed of sound. Flow regimes are classified based on this number.

Step 1: Categorize the Mach regimes.

• D. Subsonic: $M < 0.8$
• B. Transonic: $0.8 \le M \le 1.2$
• A. Supersonic: $1.2 < M < 5.0$
• C. Hypersonic: $M \ge 5.0$

Step 2: Escalating order.
Arranging from the smallest to largest Mach number gives: Subsonic $\rightarrow$ Transonic $\rightarrow$ Supersonic $\rightarrow$ Hypersonic (D, B, A, C).