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I am having some difficulty getting to the right answer for the first question.

ID: 1829176 • Letter: I

Question

I am having some difficulty getting to the right answer for the first question. I don't know if I'm doing it wrong or the program I have to use is being dumb. Any help will be appreciated.





Thank You!

A plot of force versus total sample length in a tensile test of a polymer is shown in the figure below (Figure 1). The sample is cylindrical, with an initial diameter of 1.0 cm and an initial length of 10 cm. You may want to review ( pages 188 - 193). Calculate the modulus. Express your answer to two digits and include the appropriate units. Calculate yield stress. Express your answer to two digits and include the appropriate units. Calculate yield strain. Express your answer using two digits. Calculate tensile strength. Express your answer to two digits and include the appropriate units. Calculate % elongation. Express your answer using two digits.

Explanation / Answer

the above F vs length graph is just equvalent to stress strain graph

a) modulus = stress/strain

stress = force /area = 800/(pi*(0.01^2)/4) = 10.18*10^6

strain = change in length /origninal length = (11-10)/10 = 1/10

therefore modulus = (10.18*10^6)/(1/10) = 101.8 MPa

b) yield stress = 10.18 *10^6 = 10.18 MPa

c)yield strain = 1/10 = 0.1

d)tensile strength = breaking force /area = 1000/area = 1000/(pi*(0.01^2)/4) = 12.725*10^6 = 12.725 MPa

e) %elongation = (elongation at rupture) /original length *100 = (15.5-10)/10*100 = 55%