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Postby ClaireHW » Wed Jan 17, 2018 6:34 pm

Can someone explain why the given answers are correct?

In an diabetic process, no energy is transferred as hear. Indicate whether each of the following statements about an diabetic process in a closed system is always true, always false, or true in certain conditions (specify condition):
a) delta U = 0 (true)
b) q = 0 (always true)
c) q < 0 (always false)
d) delta U = q (true)
e) delta U = w (always true)

Alyssa Pelak 1J
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Re: 8.15

Postby Alyssa Pelak 1J » Wed Jan 17, 2018 8:01 pm

(A) true because the equation U=q+w. Since they give you that q=0 and no work is done then U=0
(B) true because they tell you that there is no heat transfer
(C) false because it says there is no heat transfer so it is not losing heat
(D) true because when work is 0, U=q+w and w=0, U=q
(E) true because there is heat transfer so the equation can be derived to U=w

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Re: 8.15

Postby Humza_Khan_2J » Fri Jan 19, 2018 10:10 am

Basically, the most important thing to note here is that the process is adiabatic. This means that q must be 0. From this fact, you can derive all of these things. Be careful, what you marked as true are only sometimes true. For example, in a), if work was done on the system, the change in internal energy would not be zero.

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