1. 12 Static Equilibrium and Elasticity
Conditions for Equilibrium
The Center of Gravity
Some Examples of Static Equilibrium
Stress and Strain
(accelerated frame, indeterminate)
Hk: 19, 21, 23, 31, 33, 41.

2. Conditions for Equilibrium

3. Center of Gravity, cg
center of gravity: the average location of weight

4. 12-3 Some Examples of Static Equilibrium

5. Q: A 70kg student lies along a board with a fulcrum at one end and a scale 2.0m away at the other end. The top of his head is directly above the fulcrum. When he is on the board as described the scale reading is 250N more than when he is off the board. Where is the cg of the student?

7. Stress and Strain

11. Q: What % shortening of a 50cm diameter concrete pillar occurs when a kg truck is balanced on top of it? What is the maximum load in kg?

14. A cube 50cm per side suffers shear strain of 1% when a shear force of N is applied along two opposite faces. What is the shear modulus of this material?

15. End

19. normal force on wheel  0

20. Summary