Consider a 10-m-long smooth rectangular tube, with a = 50 mm and b = 25 mm, that is mainta...

Consider a 10-m-long smooth rectangular tube, with a = 50 mm and b = 25 mm, that is maintained at a constant surface temperature. Liquid water enters the tube at 20°C with a mass flow rate of 0.01 kg/s. Determine the tube surface temperature necessary to heat the water to the desired outlet temperature of 80°C.