Practice question

A1v1 = A2v2, v1 = 1.8m/min = 0.03m/s, A1 = 4×10−4m2. Hole area: Ah = π(0.7×10−3)2, total A2 = 20×π×4.9×10−7≈3.079×10−5m2. v2 = 4×10−4×0.033.079×10−5≈0.39m/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 0.39 m/s. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.