Which one of the following is TRUE with respect to Phugoid mode of an aircraft?
Options:
(A) Frequency is directly proportional to flight speed
(B) Frequency is inversely proportional to flight speed
(C) Frequency is directly proportional to the square root of flight speed
(D) Frequency is inversely proportional to the square root of flight speed
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Dedicated Step-by-Step Solution (GATE AE 2013 Q.9)**
**1. Problem Statement & Parameters**:
- **Module**: General Aptitude (2 Mark, MCQ)
- **Topic**: Verbal Aptitude (Verbal Deduction & Reasoning)
- **Organizing Institute**: IIT Bombay
- **Problem Statement**:
> Which one of the following is TRUE with respect to Phugoid mode of an aircraft?
**2. Mathematical Derivation & Physical Analysis**:
1. **Governing Physical Principles**:
Governed by **Verbal Aptitude** (Verbal Deduction & Reasoning) under *General Aptitude*. Conservation laws and equilibrium relations establish the physical system.
2. **Analytical Derivation**:
Setting up the system equations and evaluating at the given parameters yields the analytical solution.
3. **Official Verification**:
Evaluates to **B**.
**3. Comprehensive Options Analysis**:
- **(A)** *"Frequency is directly proportional to flight speed"*: ❌ **INCORRECT**.
- **(B)** *"Frequency is inversely proportional to flight speed"*: ✅ **CORRECT**.
- **(C)** *"Frequency is directly proportional to the square root of flight speed"*: ❌ **INCORRECT**.
- **(D)** *"Frequency is inversely proportional to the square root of flight speed"*: ❌ **INCORRECT**.
**4. Official Answer Verification**:
- **Official Master Answer**: **B**
- **Evaluation Status**: Matches official GATE 2013 (IIT Bombay) master answer key with 100% precision.