Quiz5_rubric

# Quiz5_rubric - R. (2.0 pts) Says that H_2 has a greater...

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1a) Q) (4 pts) Both gases have 3 Translational Kinetic energy modes, and are at the same temperature, so they have the same kinetic energy per molecule. Since the H_2 is lighter, it moves faster. (3.5 pts) Says that H_2 is faster because it is lighter, but does not make it clear that the kinetic energies are the same. Lighter = Faster only applies if the kinetic energies are the same. In some cases R is given instead of Q for other minor errors. R. (3.0 pts) Says the KEs are the same, but comes to the wrong conclusion. S. (2.0 pts) Says that Ar is faster because it has more thermal energy T. (1.5 pts) Says H_2 is faster because it has more modes V. (1.0 pts) Wrong. Sometimes given even if the answer given was H_2 but the explanation was completely wrong. X. 1b) Q) (3.0 pts) Ar has a greater change in internal energy because it has more total modes. (2.5) pts) Says that Ar has a greater change in internal energy because it has more moles. Also given for other minor errors.
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Unformatted text preview: R. (2.0 pts) Says that H_2 has a greater change in internal energy because it has more modes per molecule. Also give for other major errors. S. (1.0 pts) Wrong. Sometimes given even if the answer given was Ar but the explanation was completely wrong, ie. Ar because it has fewer modes per molecule. X. Q) (3.0 pts) Delta U = 70-30 = 40J for the entire system. That energy gets split between the Ar and the H_2. Ar has 3 modes/molecule and 5 moles. H_2 has 5 modes/molecule and 1 mole. So Ar gets 3*5/(3*5+5*1) * Delta U= 3/4 * Delta U_Ar = 30J. 2. (2.5 pts) Delta U = 70+30 = 100J (This is wrong). Delta U_Ar = 100*3/4 = 75J R. (2.0 pts) Understood that the energy should be split between Ar and H_2, but didn’t fully understand how, ie Delta U_Ar = 5 / 6 Delta U S. (1.0 pts)At least got Delta U = Q + W = 70 - 30 = 40J T. (0.7 pts) At least wrote down Delta U = Q + W somewhere. V. X) (0.5 pts) Wrong....
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## This note was uploaded on 09/13/2010 for the course PHY 7A 56192 taught by Professor ? during the Winter '09 term at UC Davis.

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