Air at atmospheric pressure and with a mean velocity of 0.5 m/s flows inside a thin walled square cross-section duct of side 2.5 cm. The air is heated from the walls of the duct which are maintained at a uniform temperature by condensing steam on the outside surface. Calculate the friction factor and the heat transfer coefficient assuming the flow is both hydrodynamically and thermally fully developed. Evaluate air properties at 350 K.