A post having a hollow circular cross section supports a horizontal load P = 240 lb acting at the end of an arm that is 5 ft long (see figure). The height of the post is 27 ft, and its section modulus is S = 15 in.3 Assume that outer radius of the post, r2 = 4.5 inches, and inner radius r1 = 4.243 inches.
(a) Calculate the maximum tensile stress τmax and maximum in-plane shear stress τmax at point A on the outer surface of the post along the x-axis due to the load P. Load P acts in a horizontal plane at an angle of 30° from a line which is parallel to the (-x) axis.
(b) If the maximum tensile stress and maximum inplane shear stress at point A are limited to 16,000 psi and 6000 psi, respectively, what is the largest permissible value of the load P?
