192 CHAPTER NINE y y 0 4 PROB. 9.8 20 mm 3.6 in. U.O III. 40 mm 20 mm PROB. 9.13 2.4 in. 20 mm 60 mm 40 mm 1.2 in.

Y 1.2 in. SI units 1 ... PROB. 9.12 PL25 X 300 PL25 X 450 4L127 X 127 X 19.0 PROB. 9.17 W10 X 22 3.5 in. 12 C8 X 11.5 R + 8/n9.45 A particular manufacturer offers wooden I-joists with the following dimensions: W = 2-5/16 in., d = 16 in., t = 3/8 in., f = 1-1/2 in. Find the moment of inertia about the centroidal x-axis for this cross section. 9.46 Same as Prob. 9.45 but with the following dimensions: W = 58.7 mm, d = 406 mm, t = 9.5 mm, f = 38 mm. d X- W Center of Gravity, Centroids, and Moments of Inertia of Areas I (b) PROB. 9.48 X PROB. 9.45 and PROB. 9.46 (a) (c) 205 9.10 POLAR MOMENT OF INERTIA In the analysis and design of circular bars in torsion, the po- lar moment of inertia of the cross-sectional area of the bar is required. Consider the cross section shown in Fig. 9.28. The prod- uct of the area AA; and the square of the distance r; from the origin O (or z axis) to the centroid of the area is called the polar moment of inertia for the area AA;. Adding the polar moments of inertia for each area, we find the total approxi- mate polar moment of inertia J, that is, J = Σr²AA; (9.11) S 1 + C/nFile Home Insert Draw Design Layout References Mailings Review View Help Acrobat PROTECTED VIEW Be careful-files from the Internet can contain viruses. Unless you need to edit, it's safer to stay in Protected View. Page 1 of 1 139 words Text Predictions: On 1) (2 pts) Draw two irregular but symmetric shapes and indicate the centroid by inspection Enable Editing Complete the following 2 textbook problems. Make sure all parts of these problems are completed - follow HW format - you will be graded on your work. Box all answers and use correct units. Attach all work. 2) (3 pts) Determine the centroid using computational methods. 9.11 9.13 9.15 3) (5 pts) For the area shown determine moments of inertia with respect to the centroidal axes, Ixc and Ive. 9.47 9.45 9.41 Focus C Comments I € Viewing Share X + 84%