{
  "correct_letter": "D",
  "correct_formula": "e = (v_2f - v_1f) / (v_1i - v_2i)",
  "annotation": "Environment: g=-9.81, F_drag=0.0\nGround: mu_s=0.0, mu_k=0.0\nWalnutCube1: a = 2.0, e = 0.5, m = 5120.0, v_0 = 1.5\nOakCube: a = 2.0, e = 0.5, m = 6000.0, v_0 = -1.5",
  "choices": [
    "v_1f = (m_1 - e·m_2)·v_1i / (m_1 + m_2) + v_2i·cosθ",
    "σ = F/a² = E·ε",
    "E = h·f",
    "e = (v_2f - v_1f) / (v_1i - v_2i)"
  ],
  "correct_index": 3,
  "physics_type": "InelasticCollision",
  "seed": "InelasticCollision|benchmark/inelastic_collision/3"
}