{
  "correct_letter": "B",
  "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\nGrogFiredClayCube: a = 2.0, e = 0.2, m = 16000.0, v_0 = 2.5\nWalnutCube: a = 2.0, e = 0.5, m = 5120.0, v_0 = 0.0",
  "choices": [
    "U = -G·m_1·m_2 / r",
    "e = (v_2f - v_1f) / (v_1i - v_2i)",
    "ΔE_loss = (1/2)·e²·(m_1·m_2)/(m_1+m_2)·(v_1i + v_2i)²",
    "W_f = ∫ μ_k·m·g·ds = ΔE_k"
  ],
  "correct_index": 1,
  "physics_type": "InelasticCollision",
  "seed": "InelasticCollision|benchmark/inelastic_collision/1"
}