$1.$ Comparing materials using measured data $[20$ pts$]$

The table below shows data collected for two materials: poly$($ethylene$)$ and poly $($tetrafluoroethylene$).$

A$.$ Plot the stress$-$strain curves for both materials with $\backslash (\backslash$mathrm$\{$x$\},\backslash$mathrm$\{$y$\}\backslash )$ axis labels and units. Then calculate the Young's Modulus $($ E $)$ for each material. Show both materials on the same plot to allow easy comparison. $(5$ pts$)$ Hints: Calculate E for each material by using the linear region of each plot. This is the elastic region in the notes. Do not use the plastic region for calculation of E$.$ Please

remember, YM is one number for each material and not a series of numbers.

B$.$ Using the graph from part A$,$ for each material determine the approximate strain energy before plastic deformation begins. $(5$ pts $)$

Hint: Display $\backslash (\backslash$mathrm$\{$U$\}\_\{0\}\backslash )$ calculations in MPa. Choose a stress value that is in the linear region for both the plots. Draw a straight line parallel to x $-$axis that crosses the linear section of both the plots. Use the corresponding stress and strain values to calculate strain energy. You can always use the table to get the exact strain values from linear region, if needed.

C$.$ Compare the Young's Moduli and strain energies for both materials. What do these calculations tell us about the properties of these materials? $(2$ pts$)$