Mercury flows inside a copper tube 9 m long with a 5.1- cm inside diameter at an average velocity of 7 m/s. The temperature at the inside surface of the tube is 38°C uniformly throughout the tube, and the arithmetic mean bulk temperature of the mercury is 66°C. Assuming the velocity and temperature profiles are fully developed, calculate the rate of heat transfer by convection for the 9-m length by considering the mercury as
(a) an ordinary liquid and
(b) liquid metal. Compare the results.