9.7 An oil with k = 0.120 W/(m K), Cp = 2000 J/(kg K), p = 895 kg/m, = 0.0041 kg/m s flows through a 2 cm diameter tube which is 2 m. long. The oil is cooled from 60C to 30C. The mean flow velocity is 0.4 m/s, and the tube wall temperature is maintained at 24C (uw = . 0.021 kg/m s). Calculate the heat transfer rate.