{
  "correct_letter": "B",
  "correct_formula": "m_1·v_1i + m_2·v_2i = m_1·v_1f + m_2·v_2f",
  "annotation": "Environment: g=9.81, F_drag=!=0\nGround: e=0.5\nFloorball: d = 0.07, e = 0.86, m = 0.02, h = 0.77, v_0 = 0.0\nSteelBall: d = 0.04, e = 0.6, m = 0.26, h = 0.77, v_0 = 0.64",
  "choices": [
    "h_next = e²·h_current",
    "m_1·v_1i + m_2·v_2i = m_1·v_1f + m_2·v_2f",
    "v_cm = (m_1·v_1i² + m_2·v_2i²) / (m_1·v_1i + m_2·v_2i)",
    "PV^γ = constant"
  ],
  "correct_index": 1,
  "physics_type": "Composition",
  "composition_sources": [
    "InelasticCollision",
    "Projectile"
  ],
  "choice_sources": [
    "Projectile",
    "InelasticCollision",
    "InelasticCollision",
    "Projectile"
  ],
  "seed": "Composition|Composition/2",
  "is_realworld": true,
  "dropped_wrong_formulas": [
    "InelasticCollision: W_f = ∫ μ_k·m·g·ds = ΔE_k",
    "Projectile: F_drag = (1/2)·C_d·ρ·A·v² (A = π·(d/2)²)"
  ]
}