EF 152 Exam #3, Fall, 2012 Page 1 of 6

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1 EF 5 Exam #3, Fall, 0 Page of 6 Name: Setion: Guidelines: ssume 3 signifiant figures for all given numbers. Sow all of your work no work, no redit Write your final answer in te box provided - inlude units for all answers.. ermal Expansion Linear l α l 0 Linear, Stresses σ αe Volumetri V β V 0 Ideal Gas Law pv nr R 8.34 J/(mol-K) vogadro s Number: 6.0x0 3 Standard Pressure and emp 73K.00 atm (0.3kPa) st Law of ermodynamis U internal energy W work done by termal system eat flow into termal system U W + B Conversions al 4.86 J L 000 m 3 m L B Moleular ermal Pysis m mass of a moleule M moleular mass n number of moles N number of moleules k Boltzmann onstant J/ K U N m v 3 U nr 3R 3k v rms M m Work of ermal Systems W V V pdv Isobari (onstant pressure) W p( V B V ) n p Isoori (onstant volume) W 0 n v Isotermal (onstant temp) V W nr ln V W diabati ( 0) W p V p γ pv γ ( V ) onstant γ V onstant Effiieny General W η Otto Cyle r ompression ratio η γ r Carnot Cyle η Water Properties al/(g- C) 4.86J/(g- C) L f 79.6 al/g L v 540 al/g ρ g/m 3 kg/l 000 kg/m lb/ft 3 L f Latent eat of fusion L v Latent eat of vaporization B B Heat eat speifi eat κ termal ondutivity R termal resistane Heat Capaity m ermal Condutivity t κ L R ermal Resistane L R κ ermal Resistane, Series R eff R + R ermal Resistane, Parallel R eff + Entropy B d S R + R Refrigerators General K oeffiient of performane H eat urrent P power input W + K Carnot K Carnot W H P S S mln Ideal Gas B VB S Cv ln + nr ln V

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3 EF 5 Exam #3, Fall, 0 Page 3 of 6. (4 pts).6x0 7 J of eat is added to 5 L of water tat is at 30 C. Determine te perentage of te water tat is onverted to steam.. (4 pts) n outside wall of a ouse is 9 ft ig and 40 ft long. e wall as a termal resistane of R- ft -- F/Btu. e wall ontains a window tat measures 4 ft ig and 0 ft long. e window as a termal resistane of R-7 ft -- F/Btu. Determine te number of BUs lost troug te wall system in our if tere is a 35 F temperature differene between te inside and outside.

4 EF 5 Exam #3, Fall, 0 Page 4 of 6 3. (4 pts) 0.3 m 3 tank ontains 0.8 kg of nitrogen at 0 C. Determine te gage pressure of te tank. (moleular weigt of nitrogen 4) 4. (4 pts) Determine te amount of work done by a eat engine during one yle as sown. ere are 3 moles of gas in te system. p 600 kpa 0 kpa Constant emperature 0.05 m m 3 V

5 EF 5 Exam #3, Fall, 0 Page 5 of 6 5. (4 pts) refrigerator extrats 43 kj of eat at -0 C from inside and exausts 53 kj of eat into a 8 C room. Determine te oeffiient of performane of te refrigerator as a perentage of te Carnot oeffiient of performane. 6. (4 pts) 30 kg blok of ie at 0 C is plaed in a 3 C large room. Determine te total ange in entropy of te system wen te ie just melts (turns to water at 0 C).

6 EF 5 Exam #3, Fall, 0 Page 6 of 6 7. ( pts) One metod of getting a tigt fit of a metal peg in a ole in a metal blok is to manufature te peg sligtly larger tan te ole. e peg is ten inserted wen at a different temperature tan te blok. Sould te blok be otter or older tan te peg during insertion? a) otter b) older 8. ( pts) wo objets are made of te same material, but ave different masses and temperatures. If te objets are brougt into termal ontat, wi one will ave te greater temperature ange? a) te one wit te iger initial temperature b) te one wit te lower initial temperature ) te one wit te greater mass d) te one wit te smaller mass e) te one wit te iger speifi eat 9. ( pts) Wat is te ange in internal energy in a onstant volume proess? a) W b) W ) d) e) 0 0. ( pts) How mu eat flows into a system if te internal energy derease by 0 J and te system does 30 J of work? a) -0 J b) 0 J ) -50 J d) 50 J. ( pts) Wi ylial proess represented by te two losed loops, BCF and BDE, on te PV diagram in te figure below produes te greatest net work? a) yle BCF b) yle BDE ) bot produe te same amount of net work. ( pts) e pressure of a gas is doubled wile te temperature remains onstant. Wat appens to te internal energy? a) internal energy doubles b) internal energy stays te same ) internal energy is ut in alf d) not enoug information 3. ( pts) e absolute temperature of a mole of gas doubles. Wat appens to te rms speed of te moleules? a) v rms stays te same b) v rms inreases by.4 ) v rms doubles d) v rms inreases by 4 4. ( pts) diatomi moleule as ow many degrees of freedom? a) b) ) 3 d) 4 e) 5 f) 6