Z. A 120 mm T The tube shown is made of 2014 aluminum alloy with yield strength of 276 MPa. We want to select a stock-size tube from the given table using a factor of safety N=4 Bending load is F=1.75 kN, P=9.0 kN and T=72 N.m After you pick the size for the tube, calculate the factor of safety again. w unit weight of aluminum tubing, lbf/ft w, unit weight of steel tubing, lbf/ft munit mass, kg/m A area, in (cm) k radius of gyration, in (cm) F Z = section modulus, in (cm) dxt I second moment of area, in* (cm) J = second polar moment of area, in* (cm) size (OD) and thickness, in (mm) Size, mm m A Z 12 X 2 0.490 0.628 0.082 0.361 0.136 0.163 16 x 2 0.687 0.879 0.220 0.500 0.275 0.440 16 x 3 0.956 1.225 0.273 0.472 0.341 0.545 P 20 X 4 1.569 2.010 0.684 0.583 0.684 1.367 25 X 4 2.060 2.638 1.508 0.756 1.206 3.015 25 X 5 2.452 3.140 1.669 0.729 1.336 3.338 X 30 X 4 2.550 3.266 2.827 0.930 1.885 5.652 30 X 5 3.065 3.925 3.192 0.901 2.128 6.381 42 X 4 3.727 4.773 8.717 1.351 4.151 17.430 42 X 5 4.536 5.809 10.130 1.320 4.825 20.255 50 X 4 4.512 5.778 15.409 1.632 6.164 30.810 50 X 5 5.517 7.065 18.118 1.601 7.247 36.226