1.4-1 a hollow circular post abc (see figure) supports a load p1 51700 lb acting at the top. a second load p2 is uniformly distributed around the cap plate at b. the diameters and thicknesses of the upper and lower parts of the post are dab 51.25 in., tab 5 0.5 in., dbc 5 2.25 in., and tbc 5 0.375 in., respectively. (a) calculate the normal stress s ab in the upper part of the post. (b) if you want the lower part of the post to have the same compressive stress as the upper part, what should be the required magnitude of load p2?