1. ME221Lecture 101 ME 221 Statics Lecture #10 Sections 9.7 - 9.9

2. ME221Lecture 102 Homework #4 Chapter 4 problems: –52 & 54 Chapter 9 problems –2, 11 & 32 –Due Monday, June 14 MatLab Group Problems –4.13 – plot as a function of R with 0º < α < 45º –4.51 – plot as a function of length “l” –4.60 – plot the equivalent force and point of action –Due Monday, June 14

3. ME221Lecture 103 Last Lecture Principal Second Moments Product Moment of Inertia Principal Axes Mohr’s Circle

4. ME221Lecture 104 Mechanics Nomenclature Polar Moment of Inertia = Torsional Stiffness Second Moment of Area = Bending Stiffness

5. ME221Lecture 105 Product Moment of Inertia (Product Moment of Area) Basic section with two axes of symmetry x y Composite sections - product parallel axis theorem

6. ME221Lecture 106 Mohr’s Circle for Principal Inertia (Second Moment of Area about any Axis) +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 section analyzed.

7. ME221Lecture 107 More Chapter 9 Examples