A horizontal pipe of diameter 0.942 m has a smooth constriction to a section of diameter 0.5652 m . the density of oil flowing in the pipe is 821 kg/m³ . if the pressure in the pipe is 8240 n/m² and in the constricted section is 6180 n/m² , what is the rate at which oil is flowing? answer in units of m³ /s.