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Question 31020
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Kinetic Theory and Thermodynamics: Equipartition MCQ

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EquipartitionHardQuestion 31020

Question

For a solid (Einstein model), energy per atom is 3kT because:
  1. A
    3 translational DOF only
  2. B
    6 quadratic terms (3 KE + 3 PE in harmonic oscillators)
    Correct
  3. C
    3 rotational DOF only
  4. D
    Only 1 DOF active

Correct answer

6 quadratic terms (3 KE + 3 PE in harmonic oscillators)

Explanation

Each atom in a solid can oscillate in 3 directions, each with KE and PE energy terms → 6 × (kT/2) = 3kT total. This gives Dulong-Petit molar heat capacity 3R ≈ 25 J/mol·K.

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