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q6-ef152-2008-08-soln

# q6-ef152-2008-08-soln - EF 152 Exam#6 Fall 2003 Page 1 of...

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Unformatted text preview: EF 152 Exam #6. Fall, 2003 Page 1 of? EF 152 Exam #5. Fall, 2003 Pam” a” Name: :3 -“ _ -’ Section: IL 3 1a [3 otsJ The cycle ofa heat engine consists otfour processes. as shown in the ﬁgure. Fill in the blanks in the following table with +_ —. or 0 to tndicate whether the quantityr increases. decreases. or stays the same Each box Guidelines: is worth 1 paint a Assume 3 signiﬁcant figures for all given numbers unless olherwise slaled a Show all ol your work - no work. no credit 0 Write yew final answer In the box provided 0 Include units for all answers - Include directions for all veclors Entropy Work of Thermal Systems Molecular Theme! Physics "‘ do ‘ m — mass of a molecule AS = _— If = hull" M— molecular mass I I I. 17- number olmoles N — number of molecules NJ [change in internal W [work done by heat 0 [heal flow into thermal ener enine s stem M T I, lsobariciconstant grassure] \ ham-1% + "Mar—t “xi = p03. — V.) u = .m-Gmrw‘} J I' ' .-_\Q = min-3T ' I I W .' = " Ideal Gas Law n, = u U NH pl- 2 uer 3Q = "f: 53'" IW lﬁ RZB'SMJﬂmm-K} Isothermal {constant temg} = '— = l—' I ‘ - J . . I”. = A.“ ' 1t .1! 1'. m k = 1.3mm?“er “z 2 "RT ml LIL Avooadro's Number: 6.02:1023 '”’ . i-', Efﬁciency General _ w o. a ' IQ. Adiabatic WM Mr) 2 If) 273K 1.00 am [101.3kPa} Adlabalic n =0 .3 — H’Iﬂ =‘;1{p.rly4 _p.#V;r) one Clio-[e 1"Law of Thermodynamics -” _ r _ com ression ram U - internal energy - I D W — work done by lhermal ‘ - a, = I _ I system ,---"'l 0 v heal flow into Ihermal Carnot Czcle system 1,. Q I T a = 1 _ _( ;_-' = _ AU = _w4_»n + Q-lu-Jl Tl IQ*l = Rsfdgerators —— Water Properties ELM _ , 1b [8 pts} Three different voltages are measured in a Circuit: -1Cl volts. +6 volts. and +8 volts. Determine the root- 6 = 1 calllg-“CJ = «mongrel “Emma”! 0‘ “allowance mean-square trms: voltage. L, = ?9_5 caffg H — heal current 1., = 540 calrg P — power input 9 = 1 glcm3 = I3 kglL 3 = 1000 kgi’m = 62.4 lb!“ Q). = W + Q‘ L,= Latent heat 0! fusion Qll H LV = Latent heat ol vaporization = _W| = F Carnot K {'mer _ 69 Forgot: to dwde. bu 3 @ Did ml mm square. root @ m unit-E. EF 152 Exam #6, Fall, 2008 Page 3 of ? EF 152 Exam #6. Fall, 2008 Page 4 or r 2. Cheryl's backyard nuclear power plant generates 2000 MW of heat energy from nuclear reactions in the . . . 4. Calculate the change In entropyr of 2 kg otwater when it is heated from 50°F lo 95°F reactors core. The energy is used to Don water and produce high-pressure steam at 300°C. The steam spins a turbine. which produces mt) MW of electric power. The steam is then condensed and the water Is cooled to 30‘0 _, before starting the cycle again. I . j Ca -- . . . ‘3 | / a Delermine the actual eﬂrcrency of the plant b. Determine the maximum possible thermal efﬁciency of the plant a) _ . b) _J I «2 {f lemme 2 “Q g2 wt” w’ng correct efmzéim. @Uﬁeﬁl Temp; {(1 0C M £9 U666 fl= r“ €31 rnsmd or 72,5“ . . . , 5. The rms speed at the molecules tn 30 grams of argon gas Is 410 rnts Determine Ihe temperature of the gas. 3. Calculate the change In entropy when one mole of liqUId nitrogen at—195.8°C vaporizes into nitrogen gas at me molecular mass of argon is 409fmote -195.B°C. The motecutar mass of nitrogen is 23, and the heal of I.raporiziltion of nitrogen is 201 Jig. @ used Temp to DC ,% Usgd A‘s ‘— chn 2%- Fauna 1' "T? Z F‘ E) W l- 4 usad ’25??— oozzrroz’moumLcSB EF 152 Exam #5, Fall, 2008 Page Set? EF 152 Exam #6, Fall, 2008 PageSof? 6 Determine the average transtational kinetic energy per molecule of a gas at room temperature. 20“?) a An Otto cycle is shown in the fotlowing Figure. Determine the amount work done during one cycle Assume the gas is an ideal diatomic gas with v=‘|.4. Adiabatic Adiabatic 0 0:131:10" m‘ 0 510x10" m" 'i'. Three kilograms of water at 0‘0 are placed in a freezer. Determine the amount of heat energy exhausted to the room as the water is changed to ice at 0°C. The coeffictent of performance or the treezer is 4 m. Ah‘a u'“ '1- Vnpum m'T- ﬁr“ ...
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