Subtopic: Lagrangian & Hamiltonian Dynamics & Special Relativity
Question Statement:
A particle moving under the influence of a central force r k r F
) ( (where r is the position
vector of the particle and k is a positive constant) has non-zero angular momentum. Which of the
following curves is a possible orbit for this particle?
Options:
(A) A straight line segment passing through the origin.
(B) An ellipse with its center at the origin.
(C) An ellipse with one of the foci at the origin.
(D) A parabola with its vertex at the origin.
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE PH 2016 Q.20)**
**1. Theoretical Formulation & Physics Principles**:
This question examines concepts in **Classical Mechanics** within *Section 2: Classical Mechanics* (1 Mark, 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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