A conveyor belt is driven by a 7-hp motor turning at 1,100 rpm. Through a series of gears that reduce the speed, the motor drives the belt drum shaft at a speed of 12 rpm. If the allowable shear stress is 9.3 ksi and both shafts are solid, calculate(a) the required diameter of the motor shaft.(b) the required diameter of the belt drum shaft.

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.