TakeQuiz

• Units• 32.174lbm*ft/s2 perlbf• 2.20462lbmperkg• 3.28084ftperm

• HWreview• Problem1• Reviewtheproblem,andyourapproach.

• Aloneorwithyourneighbor,organizetheproblem• Breakitup• Whataretheparts?• Whatisthemainidea?• Whatisthe“supportingcast”

HW—Problem1• Bigpicture

• Oneequation,1unknownf(v)• Putinf(v)=0form

• SubtractPfrombothsides• Usesolver:cellforV,cellforf(V)

• Supportingcast• Othervariables:P,R,T,a,b• Units:

• ConvertTtoK• Useconsistentunits:cm3,mol,bar,K• Choosegasconstant:Wikipedia

• CellsforP,R,T,a,b• CellforV• Cellforf(V)• GuessV=RT/P(idealgaslaw)• Solver:

• setcell[f(v)]toavalueof[0]• bychangingcell[V].

HW—Problem1• Bigpicture

• Oneequation,1unknownf(v)• Putinf(v)=0form

• SubtractPfrombothsides• Usesolver:cellforV,cellforf(V)

• Supportingcast• Othervariables:P,R,T,a,b• Units:

• ConvertTtoK• Useconsistentunits:cm3,mol,bar,K• Choosegasconstant:Wikipedia

• CellsforP,R,T,a,b• CellforV• Cellforf(V)• GuessV=RT/P(idealgaslaw)• Solver:

• setcell[f(v)]toavalueof[0]• bychangingcell[V].

Thisproblemisessentiallythesameastheproblemswedidinclass1equationin1unknown

Theequationisslightlyharderandhasafewotherknownparameters.

Problemthatarise:(1) Beverycarefulenteringtheformula;checkparentheses,signs(2) Beverycarefulwithunits;writethemalloutonpaperfirst

(3) Writeeachknownparameterwithunitsinadifferentcell(don’t“hardcode”thevalues)

HW—Problem3• Bigpicture

• Two2unknowns:x1,T• Putinf(v)=0form• Nosingleapproach

• Approach• Listallvariables:y1,y2,x1,x2,P,T,P1

s,P2s

• (TreatA,B,Casknownparameters)• 8variables

• Listallequations/values(weshouldget8)• Wecouldsolve8equationsin8

unknowns,butthatisoverkill• Massagetheequations

• 7and8areknownvalues• Solve3fory2.• Insert5and6into1and2• Replacex2 with1-x1 in1and2

• Nowwehave2equationsin2unknowns.

• BestWay• Writeoutall8equations,butonlyusethe

solverfor2equationsin2unknowns.Noalgegraneeded.

y1P = x1Ps1 (T )

y2P = x2P22 (T )

y1 + y2 = 1

x1 + x2 = 1

P s1 = P 2

1 (T ) = exp

A1 �

B1

T + C1

�

P s2 = P 2

2 (T ) = exp

A2 �

B2

T + C2

�

y1 = 0.33

P = 120kPa

1

2

3

4

5

6

78

HW—Problem3

y1P = x1Ps1 (T )

y2P = x2P22 (T )

y1 + y2 = 1

x1 + x2 = 1

P s1 = P 2

1 (T ) = exp

A1 �

B1

T + C1

�

P s2 = P 2

2 (T ) = exp

A2 �

B2

T + C2

�

y1 = 0.33

P = 120kPa

1

2

3

4

5

6

78