热力学中美课后答案

SOLUTION:HOMEWORK1:CH1&CH2THERMALSYSTEMSPROFESSORTHOMASHAMADEPRACTICEALLTHEEXAMPLEPROBLEMS:CH1&CH2DOTHEFOLLOWINGPROBLEMS:CH1:1-13E,1-16E,1-33E,1-34ECH2:2-17C,2-19E,2-23E,2-30E,2-31,2-50,2-56ADDITIONALPROBLEMS:UNITCONVERSION,MUSTSHOWCONVERSIONSEQUENCEEQUATIONINDETAILSUSINGCONSISTENTUNITS.PressureConversion:1ATM=?PSI=?PaHeatCapacity:1Calorie/g.0C=?BTU/lbm.0FEnergy:1Joule=?W.s=?N.m=?Kg(f).m=?Calories=?BTU1-13ETheweightofamanonearthisgiven.Hisweightonthemoonistobedetermined.AnalysisApplyingNewton'ssecondlawtotheweightforcegiveslbm4.180lbf1ft/slbm174.32ft/s10.32lbf18022gWmmgWMassisinvariantandthemanwillhavethesamemassonthemoon.Then,hisweightonthemoonwillbelbf30.722ft/slbm174.32lbf1)ft/s47.5)(lbm4.180(mgW1-16EThemassofanobjectisgiven.Itsweightistobedetermined.AnalysisApplyingNewton'ssecondlaw,theweightisdeterminedtobelbf9.9522ft/slbm174.32lbf1)ft/s0.32)(lbm10(mgW1-33EAmanisconsideringbuyinga12-ozsteakfor$3.15,ora320-gsteakfor$2.80.Thesteakthatisabetterbuyistobedetermined.AssumptionsThesteaksareofidenticalquality.AnalysisTomakeacomparisonpossible,weneedtoexpressthecostofeachsteakonacommonbasis.Letuschoose1kgasthebasisforcomparison.Usingproperconversionfactors,theunitcostofeachsteakisdeterminedtobe12ouncesteak:$9.26/kgkg0.45359lbm1lbm1oz16oz12$3.15=CostUnit320gramsteak:$8.75/kgkg1g1000g320$2.80=CostUnitTherefore,thesteakattheinternationalmarketisabetterbuy.1-34EThethrustdevelopedbythejetengineofaBoeing777isgiventobe85,000pounds.ThisthrustistobeexpressedinNandkgf.AnalysisNotingthat1lbf=4.448Nand1kgf=9.81N,thethrustdevelopedcanbeexpressedintwootherunitsasThrustinN:N103.785lbf1N4.448)lbf000,85(ThrustThrustinkgf:kgf103.854N9.81kgf1)N108.37(Thrust52-17CProbably,butnotnecessarily.Theoperationofthesetwothermometersisbasedonthethermalexpansionofafluid.Ifthethermalexpansioncoefficientsofbothfluidsvarylinearlywithtemperature,thenbothfluidswillexpandatthesameratewithtemperature,andboththermometerswillalwaysgiveidenticalreadings.Otherwise,thetworeadingsmaydeviate.2-19EAtemperatureisgiveninC.ItistobeexpressedinF,K,andR.AnalysisUsingtheconversionrelationsbetweenthevarioustemperaturescales,T(K]=T(C)+273=18C+273=291KT(F]=1.8T(C)+32=(1.8)(18)+32=64.4FT(R]=T(F)+460=64.4+460=524.4R2-23EThetemperatureofairgiveninCunitistobeconvertedtoFunit.AnalysisUsingtheconversionrelationbetweenthetemperaturescales,F30232)150)(8.1(32)C(8.1)F(TT2-30EThemaximumpressureofatireisgiveninEnglishunits.ItistobeconvertedtoSIunits.AssumptionsThelistedpressureisgagepressure.AnalysisNotingthat1atm=101.3kPa=14.7psi,thelistedmaximumpressurecanbeexpressedinSIunitsaskPa241psi14.7kPa3.101)psi35(psi35maxPDiscussionWecouldalsosolvethisproblembyusingtheconversionfactor1psi=6.895kPa.2-31Thepressureinatankisgiven.Thetank'spressureinvariousunitsaretobedetermined.AnalysisUsingappropriateconversionfactors,weobtain(a)2kN/m1500kPa1kN/m1)kPa1500(2P(b)2skg/m1,500,000kN1m/skg1000kPa1kN/m1)kPa1500(22P(c)2skg/km0001,500,000,km1m1000kN1m/skg1000kPa1kN/m1)kPa1500(22P2-50Adiverismovingataspecifieddepthfromthewatersurface.Thepressureexertedonthesurfaceofthediverbywateristobedetermined.AssumptionsThevariationofthedensityofwaterwithdepthisnegligible.PropertiesThespecificgravityofseawaterisgiventobeSG=1.03.Wetakethedensityofwatertobe1000kg/m3.AnalysisThedensityoftheseawaterisobtainedbymultiplyingitsspecificgravitybythedensityofwaterwhichistakentobe1000kg/m3:33kg/m1030)kg/m0(1.03)(100SG2OHThepressureexertedonadiverat30mbelowthefreesurfaceoftheseaistheabsolutepressureatthatlocation:kPa404.0223atmN/m1000kPa1m))(30m/s)(9.807kg/m(1030kPa)(101ghPP2-56Theairpressureinaductismeasuredbyamercurymanometer.Foragivenmercury-leveldifferencebetweenthetwocolumns,theabsolutepressureintheductistobedetermined.PropertiesThedensityofmercuryisgiventobe=13,600kg/m3.Analysis(a)Thepressureintheductisaboveatmosphericpressuresincethefluidcolumnontheductsideisatalowerlevel.(b)TheabsolutepressureintheductisdeterminedfromkPa1022223atmN/m1000kPa1m/skg1N1m))(0.015m/s)(9.81kg/m(13,600kPa)(100ghPPPatmSeahP