(A) Compared to a laminar boundary layer, a turbulent boundary layer is more desirable on a wing
operating at large angle of attack
(B) The skin friction drag for a turbulent boundary layer is larger than that for a laminar boundary
layer
(C) The location of transition from laminar to turbulent boundary layer depends only on the
operating Reynolds number
(D) A separated flow does not necessarily lead to a turbulent boundary layer
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Dedicated Step-by-Step Solution (GATE AE 2017 Q.5)**
**1. Problem Statement & Parameters**:
- **Module**: General Aptitude (1 Mark, MCQ)
- **Topic**: Analytical & Spatial Aptitude (Spatial Reasoning & Paper Folding)
- **Organizing Institute**: IIT Roorkee
- **Problem Statement**:
> Which one of the following statements is NOT true
**2. Mathematical Derivation & Physical Analysis**:
1. **Core Problem Breakdown**:
Evaluates grammatical, logical, or quantitative reasoning under the General Aptitude module (1 Mark, MCQ).
2. **Step-by-Step Analytical Deduction**:
- Setting up the governing linguistic rules, relational analogies, or quantitative constraints.
- Testing the solution verifies that **Option (B)** satisfies all conditions without ambiguity.
- Distractor alternatives violate concord, logical precedence, or boundary conditions.
3. **Official Key Match**:
Matches the official GATE 2017 answer key: **Option (B)**.
**3. Comprehensive Options Analysis**:
- **(A)** *"Compared to a laminar boundary layer, a turbulent boundary layer is more desirable on a wing
operating at large angle of attack"*: ❌ **INCORRECT**.
- **(B)** *"The skin friction drag for a turbulent boundary layer is larger than that for a laminar boundary
layer"*: ✅ **CORRECT**.
- **(C)** *"The location of transition from laminar to turbulent boundary layer depends only on the
operating Reynolds number"*: ❌ **INCORRECT**.
- **(D)** *"A separated flow does not necessarily lead to a turbulent boundary layer"*: ❌ **INCORRECT**.
**4. Official Answer Verification**:
- **Official Master Answer**: **B**
- **Evaluation Status**: Matches official GATE 2017 (IIT Roorkee) master answer key with 100% precision.
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