This document discusses the elastic properties of solids, including tensile stress and strain related to length, shear stress and strain related to shape, and bulk stress and strain related to volume. It provides definitions and formulas for tensile strain, tensile stress, Young's modulus, shear stress, shear strain, and shear modulus. Examples are given to show how to calculate tensions, shearing forces, and pressure increases using these elastic properties and formulas.

1. -Elastic Properties of Solids
AP Physics C
Mrs. Coyle

2. • Real objects are not rigid but can deform
under the influence of an external force.
• Remember: Hooke’s Law F=-kx

3. Elastic Properties of Solids
• Length (Tensile Stress- Strain)
• Shape (Shear Stress-Strain)
• Volume (Bulk Stress-Strain)

4. Elasticity of Length- Characteristics
•
∆L
Tensile Strain=
L
Tensile
Stress=F/A

5. Elasticity in Length
•
Tensile Stress = Y x Tensile Strain
F
∆L
=Y
A
L
• Y is known as Young’s Modulus
• Units of Y are N/m2

6. Tensile Strength
Test
• Tensile Strength
Sample

8. Ex: #30
• A steel wire of diameter 1mm can
support a tension of 0.2kN. A cable to
support a tension of 20kN should have a
diameter of what order of magnitude?
• Ans: 1cm

9. Elasticity in Shape - Shear Stress= F / A

10. Example: Shear Stress
http://www.fema.gov/plan/prevent/earthquake/fema74/chapter2_2.shtm

11. http://www.fema.gov/plan/prevent/earthquake/fema74/chapter2_2.shtm

12. Shear Stress and Shear Strain
F
∆x
=S
A
h
S is the Shear
Modulus,
Unit : N/m 2

13. Ex: #33
If the shear stress in steel exceeds 4.00x108 N/m2
the steel ruptures.
a)Determine the shearing force necessary to shear a
steel bolt 1.00cm in diameter.
Ans: a) 3.14x104 N

14. Ex: #33 cont’d
b)Determine the shearing force necessary punch
a 1.00cm diameter hole in a steel plate
0.500cm thick.
Ans: b) 6.28x104 N

15. Elasticity in Volume
∆F
∆V
= −B
A
V
B is the Bulk
Modulus
Unit: N/m2

16. • Note that ΔF/A is pressure.

17. Ex:#35
When water freezes, it expands by about 9%.
What pressure increase would occur inside
your automobile engine block if the water in it
froze?
(The bulk modulus of ice is 2.00x109 N/m2 )
Ans: 1.65 x 108 N/m2

18. Explaining the inertia ball tensions.

19. • How is ΔL affected
when you have
two same springs
in series or in
parallel pulled by
the same force?