Figure shows the schematic for the measurement of velocity of air (density = 1.2kg/m³) through a constant–area duct using a pitot tube and a water-tube manometer. The differential head of water (density = 1000 kg/m³) in the two columns of the manometer is 10 mm. Take acceleration due to gravity as 2 9.8 m/s² . The velocity of air (in m/s) is