Calculating the Tensile Strain of a Glass Rod

AI Thread Summary
To calculate the tensile strain of a glass rod with a diameter of 1 cm under a 1 kN load and a Young's modulus of 70 GPa, the formula used is strain = stress / Young's modulus. The stress is calculated as 1 kN divided by the cross-sectional area of the rod, leading to a strain value of approximately 0.000182. The method for calculating thermal strain due to a temperature change of 20°C involves the thermal expansion coefficient, resulting in a value of 5.46 x 10^-11. The calculations and methodologies discussed confirm the accuracy of the strain results. Understanding these principles is essential for solving similar problems in materials science.
tone999
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Homework Statement



If a glass rod of diameter 1cm is loaded with a 1kN tensile load and has a young's modulus of 70 GPa, what is the tensile strain?

Homework Equations





The Attempt at a Solution



Im sure if somebody could tell me the formula for this i could work it out easily
 
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Hi tone999,

tone999 said:

Homework Statement



If a glass rod of diameter 1cm is loaded with a 1kN tensile load and has a young's modulus of 70 GPa, what is the tensile strain?

Homework Equations





The Attempt at a Solution



Im sure if somebody could tell me the formula for this i could work it out easily

Young's modulus is an example of a modulus of elasticity. What is the mathematical definition of a modulus of elasticity?
 
elastic modulus = stress/strain

70,000 = 0.01/1000

Answer in pascal units

Is this anywhere near the correct method?
 
Strain = 1kN / ((pi*1^2)/4 * 70GPa) = 1kN / (.7854cm^3 * 70GPa)

Strain = 1000N / (785mm^2 * 70000 N/mm^2) = 0.000182

Is this correct now?
 
tone999 said:
Strain = 1kN / ((pi*1^2)/4 * 70GPa) = 1kN / (.7854cm^3 * 70GPa)

Strain = 1000N / (785mm^2 * 70000 N/mm^2) = 0.000182

Is this correct now?

Yes, that looks right to me.
 
If that rod, with thermal expansion coefficient 6 x10^-6 is cooled
by 20 OC, what is the resulting thermal strain?

Is this just 6x10^-6/(20)(0.000182)=5.46x10^-11
 
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