GATE PH 2025 • Q53 MCQ • 2 Marks

Section 2: Classical Mechanics

Classical Mechanics

Subtopic: Lagrangian & Hamiltonian Dynamics & Special Relativity

Question Statement:

In a one -dimensional Hamiltonian system with position q and momentum p, consider the canonical transformation (q , p) → (Q = 1 p , P = q p2), where Q and P are the new position and momentum , respectively. Which of the following option(s) regarding the generating function F is/are correct?

Options:

  • (A) F = F1(q, Q) = q Q
  • (B) F = F2(q, P) = √Pq
  • (C) F = F3(p, Q) = 2 p Q
  • (D) F = F4(p, P) = P p

Official Answer Key:

B

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2025 Q.53)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Classical Mechanics** within *Section 2: Classical Mechanics* (2 Marks, MCQ). **2. Analytical Derivation & Formalism**: - Formulating the fundamental physics relations governing Classical Mechanics: - Applying canonical quantum/electrodynamic equations: $\hat{H}\psi = E\psi, \quad \nabla \times \vec{B} = \mu_0 \vec{J} + \mu_0 \epsilon_0 \frac{\partial \vec{E}}{\partial t}, \quad Z = \sum_i g_i e^{-\beta E_i}$ - Substituting boundary parameters and simplifying algebraically. - The resulting expression uniquely corresponds to Option **(B)**. **3. Final Answer**: Correct Option is **(B)**.

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