5-11. The assembly consists of two sections of galvanized steel pipe connected together using a reducing coupling at B.The smaller pipe has an outer diameter of 18.75 mm and an

inner diameter of 17 mm, whereas the larger pipe has an outer diameter of 25 mm and an inner diameter of 21.5 mm. If the pipe is tightly secured to the wall at C, determine the maximums hear stress developed in each section of the pipe when the couple shown is applied to the handles of the wrench.