Gwhich of the following microconstituents/phases is (are) typically found in a low-carbon steel? pearlite ferrite martensite both pearlite and martensite both pearlite and ferrite austenite tempered martensite

Water at the rate of 1 kg/s is forced through a tube with a 2.5 cm inner diameter. the inlet water temperature is 15°c, and the outlet water temperature is 50°c. the tube wall temperature is 14°c higher than the local water temperature all along the length of the tube. what is the length of the tube?