A venturi meter is being use to measure the flow of air at 20C degree ( density = 1.204 kg/m^3) through a 18 cm duct equipped with a water manometer. The venturi neck has a diameter of 5.0 cm and the manometer has a differntial height of 45 cm. Using a discharge coefficient of 0.98, determine the volume flow rate of air ( in m^3/s)