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 Tensile Strain= Tensile Stress=F/A

5. Elasticity in Length Tensile Stress = Y x Tensile Strain Y is known as Young’s Modulus Units of Y are N/m 2

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

12. Shear Stress and Shear Strain S is the Shear Modulus, Unit : N/m 2

13. Ex: #33 If the shear stress in steel exceeds 4.00x10 8 N/m 2 the steel ruptures. a)Determine the shearing force necessary to shear a steel bolt 1.00cm in diameter. Ans: a) 3.14x10 4 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) 6.28x10 4 N

15. Elasticity in Volume B is the Bulk Modulus Unit: N/m 2

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 2.00x10 9 N/m 2 ) Ans: 1.65 x 10 8 N/m 2

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?