mid_term12-07-06-solution

mid_term12-07-06-solution - Optional Mid Term 105A 12(07f06...

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Unformatted text preview: Optional Mid Term 105A 12(07f06 Question 1 One kilogram of saturated liquid water is in a well-isolated piston—cylinder system where friction is ignored. Two options are under consideration to vaporize all the water. The first option involves a paddle that stirs the water. The second one involves direct heating using a flame. The water is initially at 150°C. a- What is the outside pressure necessary so the piston-cylinder system stays in equilibrium during the whole experiment? b~ Draw roughly the (p,v) and (T,s) diagram of these transformations. We focus on the first option. c- Under the best conditions, is this transformatiOn reversible? d- What is the work exchanged and entropy produced? Now we look at the second option. e- Under the best conditions, is this transformation reversible? f- What is the heat exchanged and entropy produced? g- Which of the two options is the most efficient? fix Smog; ilme Sjglevn is Eh an equilibrium :: Psgk C [50 DC) 3:. JDQC" F: bar T . / C9 6) EV} : Foul.— ..‘2\ 5‘? 4.75? —- - go -—- (D Q T“: 655°C. 33 To VqPOrIzfl wait—E’s" ) H46, Pacide flazsls viscoog Elm“ retinas-mt was lb lkc‘m’rar. E‘fd'folfl —-—-> ‘IT'fEJ’G-(‘Ltlolvc T) (bCeQS '7. ¢ mCUa—Ué) : v-VV O — . . a - l - — _ f . - k ' ww— ibaCZssog 6%.68) 346 \M :--—- “373. $7. k1— - O 2H2 Optional Mid Term 105A l2f07f06 Questionl (E75 .; m 6.3-5?) : His (@3373. 1.3m) «1-7,; .1. 4.. 3% kE/R kE/R%K NO ift'fiw'efslgxe. @5993. GENE IHU’D‘UQJQX lr'k: (“(53, 80 We; have CL {EU'EI'SLI‘DLe’ '60—} “£be W\"Cun u j AUZCX’*\N W:T>m@é“@ Q: m N—[U%*091 4" PLVWVEI> CC“ . - ' H G: mQfiakg : {L133 27495 -9521) Q: ZHLLE k: Since; we use fi‘gdefigbkfi (1:7: «TO 6—: {E ONES Jrth d?“.‘9n@; :30- W fikoukcg 1.06 ‘IDQHEV ’(‘b 03-h _. 43d— chptghbne: VVRuH-h + Wags . ‘ 2 “make "?“CV%‘VF> 3-9 CINE aflJLVqLLm-‘r 4:”)? Whit-ta [Edna a ghoulp‘ "Le, WK, {Paar}; ca . 3M2 Optional Mid Term 105A 12/07x’06 Question 2 One kilogram of air goes through a Carnot cycle ABCDA: AB and CD are isotherms. BC and DA are adiabatic. We suppose the cycle internally reversible. We give the following values. TA : 300 K, p», = 103 Pa, pa = 3x105 Pa and pa = 9x105 Pa. We will suppose that air is a perfect gas, cI3 = 1 kakng and k = 75. a- Compute the heat and work due to each transformation. b- Compute the entropy variation for each transformation. 0- What is the efficiency of this cycle? d- Draw the (p,v) and (T,s) diagrams. Include the labels A, B, C, and D {Redraw-u:le Glt'nol’ Cycle» .1— Tga'l‘lr‘netmg ._.;:> ? U n ‘ Lg— CT) ‘5“ '3' O [gunfire U- nwl H Apt 2’— C) (30 P: are flflll'lbve‘g (33:0 A; I senl‘oop‘ic. (TBS; Astral)th mu'ers'ilsta. 4:} Fri—s let/5 Rm; *3}. ms «PD . Ema-e— BC lesrl‘bP-v Uk- _ ;l - ke—l . T R "" _ “a c a; PP. fl have, %_ E k“ 50 IC__ K wil‘ln I». Hence VTt K Lit—i - ’P k 03m?) llifrbame TEQSohivfi iii '5‘ aural FR): PA % “A in . g 05 0 so (By. 3> \ to. fl VWSQ AAA?) gow B “r17 0N "E" l v ' - 2: 7.:- ‘; in A r-——T—- i .F—8 A04) 30 gel—Wk?) A? A V. n A “gm Since— ?AVA: h R l“: Prev?) GAB: vs. —-: ma. slate. was 5k: Q M PB _ mags C-{D I v-Q— T 1_ PC, a3}; some (Bag-puma QCD:\!\£_D:m "rT (_, u1.E-;—12~— ‘ J Optional Mid Term 105A 12307306 Questionz IQ (Pwoagg Berg", \Nfgc \JU :_. _. m C“: fg_ T 39 'fiC PD .. — 155k: fi:%%7(;t1§>3> [:j)-#e:.)x; Win: 4‘" 99—61;,— lb) r. +7fll<i¥ (:;;%])‘k 2: (3) fl {PRJCeSS (G n m g Q g? f}: \153' \{){ [TEZUYffhégl Liléz. £i§§JEE> F3; ’*iag '4': fiLEfi ASAB: m R __V c i M PB. \ Pravces S C V>B Senna. (tier—1 A364): m IE; 1“ :92... -; D 5/12 ...
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mid_term12-07-06-solution - Optional Mid Term 105A 12(07f06...

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