Copper (cu) has crystal structure Atomic mass of Cu is 63.55 gmol^-1 and radius of a copper atom is 0.128 nm, mean speed of conduction electrons in Cu is 1.5 ×10^6 ms^-1 and frequency of vibration of the Cu atoms at 27 °C is 4×10^12 S^-1 Nordheim’s Coefficient of Au in Cu is 5500 Ω −m Caculate (a) the atomic density of copper (b) Estimate the drift mobility of electronics in cu (c) find the resistivity of pure copper cu (d) find the resistivity of copper if 1 at % of Au is mixed in Cu

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.