{"correct_letter": "C", "correct_formula": "(1/2)\u00b7m_1\u00b7v_1i\u00b2 + (1/2)\u00b7m_2\u00b7v_2i\u00b2 = (1/2)\u00b7m_1\u00b7v_1f\u00b2 + (1/2)\u00b7m_2\u00b7v_2f\u00b2", "annotation": "Environment: g=-9.81, F_drag=0.0\nGround: mu_s=0.0, mu_k=0.0\nGlassCube: a = 2.0, e = 1.0, m = 20000.0, v_0 = 2.4\nStainlessSteelCube: a = 2.0, e = 1.0, m = 63200.0, v_0 = 0.3", "choices": ["I = I_cm + m\u00b7(a/2)\u00b2", "v_2f = 2\u00b7m_1\u00b7v_1i\u00b7cos\u03b8 / (m_1 + m_2)", "(1/2)\u00b7m_1\u00b7v_1i\u00b2 + (1/2)\u00b7m_2\u00b7v_2i\u00b2 = (1/2)\u00b7m_1\u00b7v_1f\u00b2 + (1/2)\u00b7m_2\u00b7v_2f\u00b2", "F = k\u00b7q_1\u00b7q_2 / r\u00b2"], "correct_index": 2, "physics_type": "PerfectlyElasticCollision", "seed": "PerfectlyElasticCollision|benchmark/perfectly_elastic_collision/8"}