116 exam - I. Below are six designs that were submitted for...

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Unformatted text preview: I. Below are six designs that were submitted for reversible heat engines. None have been built, and it is your job to decide which is the best design. The amount of thermal energy transferred from the hot reservoir to the engine, and fi'om the engine to the cold reservoir is shown for one cycle. The amount of work done in one cycle is also shown. a) Which of the engines, A through F, are allowable by the 1st law of thermodynamics? (show A your work) 10x.) N = scopes our" 3/ /A/ =33ur— Les 3e A: 000143; Mae MAIMTfl’v/dafi \ b) Of those that are allowable by the 1st law, which ones are also allowable by the 2nd law of thermodynamics? (show your work) 1— 6- ; new W e903! 05‘ TD 1:. 5:5 75 — 1MB ; 0) Of those that are allowable by both the 1st law AND the 21nd law of thermodynamics, which one is the most efficient? (show your work) .‘ = NO : __ To ’x// “R L ca, / T; E “A/e= FIE— %( E5 M55??— (7 \ - V315 q The P-V diagram shown at the right describes a 3-leg cyclic process. Theo 01" mass of the gas is constant. :1) Fill in the missing spaces in the table below. i a v - ressure? tem : erature? volume? y «mm m ~ T- l b) How much work is done in one cycle if: 645’ 5P1: kPa L P3= 640 kPa ’200 L v1=4.0x10‘3 m3and . 00’7’ vmljzs x 10'3 m3 . 00/25 = 7 736*:— 6) Circle the Pressure vs Temperature graph that best describes this cycle and E ’ REASONING. Explain your reasoning: misc, 7?: 71—49“ gym /—>2 1 anmr‘ T‘ir 2~>3=Piin ' I) I$W€o 6Wwa 0 swousmmss Au, 81x 3‘? i ' ‘Tcmsnssr Coubtflmgi :l t 3) An ideal gas undergoes one reversible process from a temperature T1 to a higher temperature T2. Which of the following COULD describe the process ? adiabatic, isobaric , or isovolumetric T \ isobaric or isovolumetric “‘9 2K isothermal, isobaric , or isovolumetric :- >é adiabatic or isothermal all of the above 4“) An Wgam block is heated to 200°C . The block is then quickly placed in an insulated tub of cold water at 0°C and sealed. At equilibrium, the temperature of the water and Block are measured to be 15°C. If you repeat the experiment but replacengg of the 0°C water with 50 g of 0°C ice, what is the final temperature of the water and block?; c, c. (The specific heat of the block is 418 I/kg 0 C", the specific heat of water is 4180 ]/kg 0 C ", the latent heat of fusion of water L}: 334 x 103 I/kg ) L— ,stl see-as To 475K a) 15°C L? AT: —- 2.09 ® less than 15°C ( greater than 15°C but less than 100°C (4 qug» ;/ d) 100°C ges- " (2) None of the above. Sb/(‘éeg’zC‘OS'XW XXT> I W s” a 5) You are holding a piece of metal by a rope with a tension of 4 N in a tank of water L=2m from the bottom. The rope breaks. If the piece of metal has a volume of 2.5 x 10“ m3, how long does it take to fall to the bottom of the tank? a) 0.64 s 2’ b) 0.73 s ZIP” : K ® 0.81 s M V p M d) 1.1 s ' + l3 A 3 e) 0.90 s A : 7Ml52- ( qutle: L! vas ‘7 ms ass-K 9‘5774'7’6’7 $5. ,ow ./ bl? (m2. 6) A child plays with a helium-filled balloon inside her warm house. The helium in her balloon has a density D. She takes her balloon outside and it is a very cold day. When she gets outside she notices that the balloon shrinks, and that it takes up 9/ 10 of the space that it did in her house. If no helium escapes from the balloon, then the density of the helium in the balloon after shrinking is: k 6? a) (11/10)*D “V /% in : 72: V D : fin r 7?. b) (1/10) *D‘ V °) D — fl. @am 5‘ . b = M a. a 5 e) (9/10)*D ; _ I L (c) ‘2 b2 g?" ' I A, lo v a: !0\/‘ lo mm —.> #9/‘1 7) The surface water of a community reservoir is 30 m above the level of the water faucet in your kitchen. What is the maximum possible speed with which the water can leave your faucet? / 2 L; m L? @ .24m/s El 2 g b) 31m/s A I30,” '$ girl in —- k 2 a Jew“ F3 7 e) 30m/s . (éylmx V 2) =Qooo>casi>®¢> \1 =2'1.7(W45 8) Find the net force on the Wings of an airplane that have a total area of 100 m2. The airspeedwover the wing is 133 m / s and the airspeed under the Wing is 120 m/ s. The density of the air is 1.2 kg / m3. Assume that the wing thickness is negligible. \f/‘lr 1 UK c) 28 m/s d) 26 m/s a) 4x103N #5 /00m3 b) 2x103N law/s c) 3x103N ‘\ k I 3 d) 4x105N w Fm : (’2‘ M (£3 2x105N '20“ E W, sumo 23F Ail)“. 60% (A 7W“ 1.2 \ngoow Kwfi (‘EX—nghgim/jz ...
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This note was uploaded on 02/06/2012 for the course PHYSICS 115 taught by Professor Brahmia during the Fall '08 term at Rutgers.

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116 exam - I. Below are six designs that were submitted for...

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