{
  "correct_letter": "D",
  "correct_formula": "y = h + x·tanθ - g·x² / (2·v_0²·cos²θ)",
  "annotation": "Environment: g=9.81, F_drag=!=0\nGround: e=0.5\nPingPongBall: d = 0.04, e = 0.71, h = 0.92, v_0 = 1.51",
  "choices": [
    "x(t) = v_0·t·cosθ · (1 - g·t/v_0)",
    "m·g·h + (1/2)·m·v_0² = constant",
    "U = (1/2)·k·x²",
    "y = h + x·tanθ - g·x² / (2·v_0²·cos²θ)"
  ],
  "correct_index": 3,
  "physics_type": "Projectile",
  "seed": "Projectile|Gravity/Projectile/21",
  "is_realworld": true,
  "dropped_wrong_formulas": [
    "F_drag = (1/2)·C_d·ρ·A·v² (A = π·(d/2)²)"
  ]
}