{
  "correct_letter": "C",
  "correct_formula": "y = h + x·tanθ - g·x² / (2·v_0²·cos²θ)",
  "annotation": "Environment: g=9.81, F_drag=!=0\nGround: e=0.5\nTennisBall: d = 0.07, e = 0.75, h = 1.4, v_0 = 3.99",
  "choices": [
    "a_n = v² / ρ",
    "B = μ_0·I / (2π·r)",
    "y = h + x·tanθ - g·x² / (2·v_0²·cos²θ)",
    "v_x(t) = v_0·cosθ · e^(-g·t/v_0)"
  ],
  "correct_index": 2,
  "physics_type": "Projectile",
  "seed": "Projectile|Gravity/Projectile/39",
  "is_realworld": true,
  "dropped_wrong_formulas": [
    "F_drag = (1/2)·C_d·ρ·A·v² (A = π·(d/2)²)"
  ]
}