{
  "correct_letter": "B",
  "correct_formula": "y(t) = h + v_0·t + (1/2)·g·t²",
  "annotation": "Environment: g=-9.81, F_drag=0.0\nGround: e = 0.4\nClaySphere: d = 1.0, e = 0.2, h = 6.0, v_0 = 0.0",
  "choices": [
    "n_1·sinθ_1 = n_2·sinθ_2",
    "y(t) = h + v_0·t + (1/2)·g·t²",
    "F_fall = m·g·(1 + v/c) / √(1 - v²/c²)",
    "P + (1/2)·ρ·v² + ρ·g·h = constant"
  ],
  "correct_index": 1,
  "physics_type": "FreeFall",
  "seed": "FreeFall|benchmark/freefall/0"
}