{
  "correct_letter": "B",
  "correct_formula": "F_N - m·g·cosθ = m·v²/R",
  "annotation": "Environment: g=-9.81, F_drag=0.0\nGround: mu_s=0.0, mu_k=0.0\nTireSphere: d = 1.0, e = 0.6, theta_start = 360°, v_0 = -4.0\nTrack_0: R = 2.5, e = 0.3, theta_min = 180°, theta_max = 360°, mu_s = 0.0, mu_k = 0.0",
  "choices": [
    "ΔS = Q_rev / T",
    "F_N - m·g·cosθ = m·v²/R",
    "f_s ≤ μ_s·F_N",
    "a_c = v²·cosθ / (R·sinθ)"
  ],
  "correct_index": 1,
  "physics_type": "Circular",
  "seed": "Circular|benchmark/circular_newbatch/14"
}