1. ME 221Lecture 201 ME 221 Statics Lecture #20 Sections 9.7 - 9.9

2. ME 221Lecture 202 Homework #7 Chapter 4 problems: –52, 53 & 54 Chapter 9 problems: –2, 3, 4, 11, 23, 29 & 32 –Use double integration for 2, 3, 4 & 11 Due Wednesday, October 23

3. ME 221Lecture 203 Homework #8 Chapter 9 problems: –42, 43, 50 & 55 Chapter 5 problems: –11, 13, 16, 20, 24 & 25 –See Blackboard for additional information Due Wednesday, October 30

4. Exam #2 Results Will be returned Wednesday Scores will be posted on Blackboard Solution will be posted on Blackboard See syllabus for regrade policy

5. Last Lecture Moments of Area Moments of Basic Shapes Polar Moments Parallel Axis Theorem Radius of Gyration

6. ME 221Lecture 206 Principal Second Moments Definition of product of inertia Definition of principal axes –Product of inertia axis theorem Mohr’s circle to find principal axes Example

7. ME 221Lecture 207 Product Moment of Inertia Basic section with two axes of symmetry x y Composite sections - product parallel axis theorem

8. ME 221Lecture 208 Mohr’s Circle for Principal Inertia +I xy -I xy I xx, I yy I yy x I xx I xy x draw point (I xx, I xy ) and the circle (I xx +I yy )/2 draw circle center (I xx + I yy )/2 x I MAX I MIN 22 use geometry to find I MAX, I MIN and  ANGLES IN MOHR’S CIRCLE ARE TWICE THOSE IN THE CROSS SECTION!!!

9. ME 221Lecture 209 Example