Practice question
Question
A pipe narrows from 0.06m2 to 0.02m2. If water flows at 1.8m/s in the wider section, what is the speed in the narrower section?
Explanation
Continuity equation: A1v1 = A2v2. A1 = 0.06m2, v1 = 1.8m/s, A2 = 0.02m2. v2 = A1v1A2 = 0.06×1.80.02 = 5.4m/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 5.4 m/s. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.