Abeam of rectangular cross-section is subjected to a bending moment m (n. m) and a maximum shear force v (n), the bending stress in the beam is calculated as ? -6mbh2 (pa), and average shear stress is calculated as ? ? v/2bh (pa), where b is the width and h is the depth of the beam. the allowable stresses in bending and shear are mpa and -3 mpa, respectively. it is also desirable that the depth of the beam not exceed twice its width and that the cross-sectional area of the beam be minimized. m-80 kn and v=150 kn.

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.