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Informal sessions:

o Tu 3:30-4:20pm, RAS 218;

o Fri 4-4:50pm, ECJ 1.204.

Lecture 30 (iq26)

Demos:

§ Stable equilibrium

§ Mechanical advantage: Leverage, pulley system

§ Climbing up a ladder (see also pQ125)

Elasticity of materials: Please read on your own.

Elastic modulus = stress/strain = [F/A] / [fractional deformation]

Young’s modulus	Y=[F/A] /[DL/L]
Shear modulus	S=[F/A] /[Dx/h]
Bulk modulus	B=[F/A] /[DV/V]

Hints on selected homework problems

§ Effect due to internal structure on external equilibrium forces (PQ124)

§ Static problems which involve spheres. PQ121, 122.

Remainder of this week:

· Today’s lecture: Complete Chapter 14. Please continue to work on hw 11.

· Friday’s lecture: More on HW11, and review unit 3

· Friday’s informal session: hw11, and review on unit 3 if time permit.

· Due date of HW11: 4am Nov 10. (Monday, or Sun evening)

· Midterm 3, Wed. Nov 12. 7-8:30pm.