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## -Elastic Properties of Solids

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**-Elastic Properties of Solids**AP Physics C Mrs. Coyle**Real objects are not rigid but can deform under the**influence of an external force. • Remember: Hooke’s Law F=-kx**Elastic Properties of Solids**• Length (Tensile Stress- Strain) • Shape (Shear Stress-Strain) • Volume (Bulk Stress-Strain)**Elasticity of Length- Characteristics**• Tensile Strain= Tensile Stress=F/A**Elasticity in Length**• Tensile Stress = Y x Tensile Strain • Y is known as Young’s Modulus • Units of Y are N/m2**Tensile Strength Test**• Tensile Strength Sample**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**Example: Shear Stress**http://www.fema.gov/plan/prevent/earthquake/fema74/chapter2_2.shtm**http://www.fema.gov/plan/prevent/earthquake/fema74/chapter2_2.shtm**http://www.fema.gov/plan/prevent/earthquake/fema74/chapter2_2.shtm**Shear Stress and Shear Strain**S is the Shear Modulus, Unit : N/m2**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**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**Elasticity in Volume**B is the Bulk Modulus Unit: N/m2**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**How is ΔL affected when you have two same springs in series**or in parallel pulled by the same force?