Ahollow circular nylon pipe (see fig) supports a load pa = 1750 lb, which is uniformly distributed around a cap plate at the top of the lower pipe. a second load pb is applied at the bottom. the inner and outer diameters of the upper and lower parts of the pipe are d1 = 2 in., d2 = 2.375 in., d3 = 2.25 in., and d4 = 2.5 in., respectively. the upper pipe has a length l1= 14in., the lower pipe length is l2 = 16 in. neglect the self-weight of the pipes. -if pa remains unchanged, find the new value of pb (in lb) so that upper and lower parts have same tensile stress.