Astack of fake coins there are n stacks of n identical-looking coins. all ofthe coins in one of these stacks are counterfeit, while all the coins in the otherstacks are genuine. every genuine coin weighs 10 grams; every fake weighs11 grams. you have an analytical scale that can determine the exact weight ofany number of coins. a. devise a brute-force algorithm to identify the stack with the fake coins anddetermine its worst-case efficiency class. b. what is the minimum number of weighings needed to identify the stackwith the fake coins?

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.