systems engineering written examination - specifications ... · pdf file• place the...

S A M P L ESYSTEMS ENGINEERING

Written examination

Day Date Reading time: **.** ** to **.** ** (15 minutes) Writing time: **.** ** to **.** ** (1 hours 30 minutes)

QUESTION AND ANSWER BOOK

Structure of bookSection Number of

questionsNumber of questions

to be answeredNumber of

marks

A 20 20 20B 19 19 80

Total 100

• Studentsarepermittedtobringintotheexaminationroom:pens,pencils,highlighters,erasers,sharpeners,rulersandonescientificcalculator.

• StudentsareNOTpermittedtobringintotheexaminationroom:blanksheetsofpaperand/orwhiteoutliquid/tape.

Materials supplied• Questionandanswerbookof24pagesincludingformulasonpage24.• Answersheetformultiple-choicequestions.

Instructions• Writeyourstudent numberinthespaceprovidedaboveonthispage.• Checkthatyournameandstudent numberasprintedonyouranswersheetformultiple-choice

questionsarecorrect,andsignyournameinthespaceprovidedtoverifythis.• Allcalculationsmustshowappropriateformulasandworking.

• AllwrittenresponsesmustbeinEnglish.

At the end of the examination• Placetheanswersheetformultiple-choicequestionsinsidethefrontcoverofthisbook.

Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room.

©VICTORIANCURRICULUMANDASSESSMENTAUTHORITY2013

Version3–December2017

SUPERVISOR TO ATTACH PROCESSING LABEL HEREVictorian Certificate of Education Year

STUDENT NUMBER

Letter

SYSENGEXAM(SAMPLE) 2 Version3–December2017

SECTION A – continued

Question 1Aboatwinchhasadrivergearof20teethandadrivengearof160teeth.Whatisthegearratio?A. 0.125:1B. 1:8C. 8:1D. 16:1

Question 2Whenanewproduct(forexample,anewcar)isdesignedforthemarket,extensivefield-testingisusuallycarriedoutontheproduct.ThepurposeofthistestingistocheckwhetherA. theproductwillsell.B. peoplewillliketheproduct.C. theproducthastherightrangeofcolours.D. theproductperformstoitsdesignrequirements.

Question 3

gear Z

gear Y

gear X

Inthediagramabove,ifgearXmovesclockwisethengearZwillrotateA. clockwiseandfasterthangearX.B. clockwiseandslowerthangearX.C. anticlockwiseandfasterthangearX.D. anticlockwiseandslowerthangearX.

SECTION A – Multiple-choice questions

Instructions for Section AAnswerall questionsinpencilontheanswersheetprovidedformultiple-choicequestions.Choosetheresponsethatiscorrect forthequestion.Acorrectanswerscores1,anincorrectanswerscores0.Markswillnotbedeductedforincorrectanswers.Nomarkswillbegivenifmorethanoneansweriscompletedforanyquestion.Unlessindicateddiagramsarenottoscale.

Version3–December2017 3 SYSENGEXAM(SAMPLE)

SECTION A – continuedTURN OVER

Question 4ThecorrectworksequencetoreducetheriskofinjurytoapersonisA. riskassessment,hazardidentification,riskcontrol.B. hazardidentification,riskassessment,riskcontrol.C. riskassessment,riskcontrol,hazardidentification.D. riskcontrol,hazardidentification,riskassessment.

Question 5A20-cm-longspannerisusedtoproduceatorqueof60Nm.TheforceappliedtothespannerisA. 3NB. 12NC. 120ND. 300N

Use the following information to answer Questions 6 and 7.

A

B

CD

Question 6 Thehydraulicpumpmovesfluidfromatanktotheoutlet.TherotorsAandBhaverotarymotionthatisA. clockwiseforboth.B. anticlockwiseforboth.C. clockwiseforAandanticlockwiseforB.D. anticlockwiseforAandclockwiseforB.

Question 7ThefluidpressuresareA. zeroatpointCandpointD.B. thesameatpointCandpointD.C. highatpointCandlowatpointD.D. lowatpointCandhighatpointD.



Question 8

car handbrake

X

Y

Z

Onthediagramofthecarhandbrakeleverabove,whatarethecorrectpositionsoftheeffort,loadandfulcrum?

Effort Load Fulcrum

A. X Y ZB. Z Y XC. Y X ZD. X Z Y

Question 9

500 mm

200 mm

cable

car handbrakeforce

Onthediagramabove,theforceappliedtothehandbrakeleverbytheoperator’shandis40N.Whatistheforceappliedtothecable?A. 100NB. 200NC. 300ND. 700N



Question 10AsemiconductorisusedintheconstructionofA. arelay.B. atransformer.C. alight-emittingdiode(LED).D. anelectrolyticcapacitor.

Question 11

4 nf 6 nf

Whatisthetotalcapacitanceofthecircuitshownabove?A. 2nfB. 2.4nfC. 10nfD. 24nf

Question 12Batteriescanbeconnectedinseriesorinparallel.ThemainreasonforconnectingbatteriesinparallelistoincreasetheA. availablecurrent.B. voltageavailable.C. internalresistance.D. externalresistance.



Question 13

let D1 = 0

start

stop

let D1 = 1 + D1

let D0 = 0

let D0 = 1 + D0

wait 1

wait 1

D0 = 5N

N

Y

Y

low 0

D1 = 5

high 0

Aflowchartforamicrocontrollerprogramisshownabove.‘High0’turnsanLEDon.‘Low0’turnsitoff.‘Wait1’isaone-seconddelay.HowmanytimeswilltheLEDturnonandoffinthisprogram?A. onceB. 10timesC. 20timesD. 25times

Question 14

voltage

time

Thedisplayonacathoderayoscilloscopeisshownabove.Giventhatthehorizontalscaleis0.01secondsperdivisionandtheverticalscaleis2Vperdivision,thevoltageandfrequencyoftheabovesignalareA. 3Vand1HzB. 3Vand2HzC. 6Vand50HzD. 6Vand100Hz



Question 15

driven gear

driver gear

Thedriverinthegearabovehas8teethandturnsclockwise.Thedrivengearhas22teeth.Whatisthegearratioofthedrivengeartothedrivegearandthedirectionofrotationofthedrivengear?A. 4:11clockwiseB. 4:11anticlockwiseC. 11:4clockwiseD. 11:4anticlockwise

Question 16Solderwire,usedintheconstructionofelectroniccircuitsinthepast,containedametalthatislinkedtoahealthhazard.ThishazardousmetalwasA. tin.B. iron.C. lead.D. copper.

Question 17

Forward voltage Current drawn

Green 2.1V 20mA

Blue 3.5V 20mA

Thetableaboveshowsthespecificationsfor5mmgreenand5mmblueLEDs.ThegreenLEDcomparedtotheblueoneA. haslowerresistance.B. hashigherresistance.C. consumesmorepower.D. consumesthesameamountofpower.


END OF SECTION A

Question 18

1 14 VDD + 3 –15 V

VSS 0 V

2 13

3 12

4 11

5 10

6 9

7 8

The4011integratedcircuitshownabovehasfourlogicgates.Totestthelogicgateconnectedtopins1,2and3,voltagevaluesaremeasuredandrecordedashighorlow.Whichtablebelowrepresentsthecorrectoperationofthatlogicgate?

A. B. C. D.

Pin Voltage

1 low

2 low

3 low

Pin Voltage

1 high

2 low

3 low

Pin Voltage

1 high

2 high

3 low

Pin Voltage

1 low

2 high

3 low

Question 19Anundersizedelectricalcableisselectedtoconnectapowersupplytoanoperatingcircuit.ThemajorhazardthatislikelytooccuristhattheelectricalcablewillA. break.B. overheat.C. shortcircuit.D. nothaveenoughresistance.

Question 20

VIN = 240 VAC200 windings

VOUTNs = 20

ThevalueofthevoltageacrosstheoutputwindingsisA. 12 VB. 24VC. 240VD. 2400V


SECTION B – continuedTURN OVER

The following information relates to Questions 1–18.Avehicleistobeconstructedsothatitispoweredbyanelectricengine.Therearetwomainsubsystemsinthevehicle:themechanicalsubsystemandtheelectrical/electronicsubsystem.TwopossibleoutlinesoftheconceptaregiveninFigure1.

Figure 1

Question 1 (1mark)Whyisthisvehicleconsideredtobeanintegratedsystem?

Question 2 (4marks)Oneperformancespecificationofthevehicleisthatitshouldbeabletotravelataconstantspeedfor140km.a. Givetwootherappropriateperformancespecificationsthatcouldbeincludedinthedesign

brief. 2marks

1.

2.

b. Describeatestforoneoftheperformancespecificationsthatyounamedinpart a. 2marks

SECTION B

Instructions for Section BAnswerall questionsinthespacesprovided.Unlessindicatedthediagramsarenottoscale.


SECTION B – continued

Question 3 (6marks)AsshowninFigure1,thevehiclecouldbeeitherathree-orfour-wheeledvehicle.a. Discusstwoissuesthatwouldarisewhendecidingwhichwheellayouttouse. 4marks

b. Theclienthasdecidedtoconstructathree-wheeledvehicle(tricycle). Givetwosafetyconsiderationsthatneedtobeaddressedwhendesigningthelayoutofthe

tricycle. 2marks



Question 4 (6marks)Thebuilderofthevehiclewantstoexplorethepossibilityofpoweringthevehiclewithnewtechnology.Hedoesnotwanttousefossilfuels.Atthisstage,thebuilderdoesnotwanttousesolarenergy.a. Nametworenewablesourcesofenergy(otherthansolarenergy). 2marks

1.

2.

b. Explainhowoneoftherenewablesourcesofenergythatyounamedinpart a.couldbeusedtopowerthetricycle. 2marks

c. Discussoneenvironmentaladvantageoftherenewablesourceofenergythatyoudescribedinpart b. 2marks



Question 5 (5marks)

solar panel

Thebuilderofthevehicleeventuallydecidestochargethebatteryusingsolarpanels.Thebuilderdecidestousea2m2panelthatgeneratesapeakoutputof100W.a. Calculatehowmanywattsofsolarpowerwillfallonthesolarpanelifthesolarcellsare

20percentefficient. 2marks

Theprocessofchargingthebatteryis90percentefficient.Themotorthatisusedis85percentefficient.b. Calculatethecombinedefficiencyofthebatterysystemandoperatingthemotor. 1mark

c. Whatmightbeonedisadvantageofpoweringthetricyclewithsolartechnology? 2marks



Question 6 (3marks)Onedesignoptionforthevehicleistoincorporateaself-centringsteeringmechanism.Anotherdesignoptionistohavetheshaftsatanangle.

a a

shaft

height

Figure 2

a. Whathappenstotheheightofthevehiclewhenthewheelschangedirection? 1mark

b. Intermsofpotentialenergy,explainhowtheself-centringmechanismwouldwork. 2marks



Question 7 (7marks)a. Designasafesteeringmechanismforthetricycle.Drawandlabelthepartsonthediagram

below. 3marks

b. Listtwoprocessesthatwillbeneededtoconstructthesteeringmechanism. 2marks

1.

2.

c. Giveadifferentsafetyprecautionforeachoftheprocessesthatyoudescribedinpart b. 2marks

1.

2.



Question 8 (5marks)Achainaroundthetwo-cogdrivesystemisadesignoptionforthetricycle.Dataisshowninthetablebelow.

speedoftricycle 40.0km/hor11.1m/s

rpmofaxle 600rpm

cogsavailable teethfrom10to60

motorspeed 6000rpm

a. Calculatethecircumferenceofthewheel. 2marks

b. Drawadrivesystemonthediagrambelowthatwouldsatisfytheconditionsstatedinpart a. andthetableabove.Givethenumberofteethoneachcog.Justifyyouranswerbyshowingrelevantcalculations. 3marks

motoraxle



Question 9 (4marks)Ahydraulicdiscbrakingsystemistobeusedonthevehicle.Thediameterofthediscbrakecylinderis60.0mmandthediameterofthemastercylinderis20.0mm.ThebrakingsystemisshowninFigure3.

master cylinder

brake pedaldisc brakecylinder

axle

disc

brake pads

Figure 3

a. Calculatethepressureinthesystemifaforceof120.0Nisappliedtothebrakepedal.Includeanyworkingandthefinalunits.Giveyouranswertothreesignificantfigures. 2marks

b. Calculatetheforceappliedtoeachofthebrakepads.Giveyouranswerinnewtons(N)andtothreesignificantfigures. 2marks

Question 10 (2marks)Thetricycleistobepoweredbya200Wmotorwithasupplyvoltageof40Vatmaximumoutput.Calculatethecurrentthroughthemotor.



Question 11 (3marks)Themotoristobewiredupwithaswitch,battery,ammeterandapotentiometerthatisusedtovarythespeed.Completethewiringdiagrambelow.

A M

Question 12 (5marks)AgraphofpowerconsumptionversusspeedisgiveninFigure4below.

20018016014012010080604020

5 10 15 20 25 30 35 40

Power consumption versus speed

power output (W)

speed (km/h)

Figure 4

a. UsetheinformationfromFigure4abovetocalculatetherangeofthetricycleifitistocruiseat25kmh–1.Assumethata40Vsupplytothemotoranda10Ahbatteryareused. 2marks

b. Howfarwillthetricycletravelatfullpower? 2marks

c. Explainwhythereisadifferenceintherangeofthetricycleatdifferentspeeds. 1mark



Question 13 (4marks)Thetricycledoesnotmeettheperformancespecificationofhavingarangeof140km.Givetworecommendationsforchangestothetricycleinordertomeettheperformancespecificationabove.Justifyeachrecommendation.

1.

2.

Question 14 (4marks)Someoftheprocessesintheconstructionofthetricycleareshownbelow.Constructaproductionsequenceforthetricyclebynumberingtheprocessesbelow.

Process Number

constructionofframe

computer-simulationofelectronics

constructionofsteeringsystem

installationofbrakes

mountingmotorandgearbox

simulationofmotorandgearbox

mountingwheels

wiringtheelectricalcomponents


SECTION B – Question 15 –continuedTURN OVER

Question 15 (7marks)Inordertomaintainthetricycleataconstantspeed,aspeedometerisrequired.Asystemsdiagramforaspeedometerisgivenbelow.

input device

AninputdeviceistobeattachedtothetricycletoproducethesignalshowninFigure5below.

9 volts

voltage

0 voltstime

Figure 5

a. ExplainwhythesignalshowninFigure5isconsideredadigitalsignal. 1mark

b. Nameaninputdevicethatcanbeusedonthetricycletoproducethesignalshownin Figure5. 1mark

c. Onthetricyclebelow,placetheinputdevicethatwasnamedinpart b.sothatitwillgeneratethesignal. 1mark

d. Howmanypulsesperrevolutionofthewheelarethereforthisinputdevice? 1mark



e. Drawthisinputdeviceinacircuitdiagramsothatitwillproducethegivensignal.Labelallcomponents. 3marks

Question 16 (2marks)Amicrocontrolleristobeusedtoconvertthesignaltogiveadecimaloutputthatwilllaterbereadouton7-segmentdisplays.Thepinconfigurationofan18-pinmicrocontrollerisshowninFigure6.

123456789

181716151413121110

ADC 2/input 2serial out

serial inreset

0 Voutput 0

output 1/12c sdaoutput 2

output 3/pwn 3

input 1/ADC 1input 0/ADC 0/infraininput 7/keyboard datainput 8/keyboard clock+Voutput 7output 6output 5output 4/12c scl

microcontroller

Figure 6

a. Whichpinisconnectedtothevoltagesupply? 1mark

b. Thesignalfromthesensorwillbeconnectedtoapin. Nameapintowhichthesignalcanbeconnected. 1mark



Question 17 (4marks)Themicrocontrollerwillneedtobeprogrammedtoconverttheinputsignalfromthesensorintoadecimaloutputthatgivesthevelocity.Theinputsignalisfromyourinputsensorandthecircumferenceofthewheel is1.2m.Drawaflowchartorwriteashortprogramtoperformtheprocessofconvertingtheinputsignalfromthesensorintoadecimaloutput.Anyformulausedmustbestated.



Question 18 (3marks)Themicrocontrollerhasacommandtoconvertadecimaloutputintoa4bitBinaryCounttoDecimal(BCD)signal.Thatis,abinarysignalthatcountsfrom0to9.Usingthe4bitoutputpinsofthemicrocontroller,thedecimaloutputcanbeconvertedtoaBCDsignal.(Eachdecimaldigitisrepresentedbya4bitbyte.)Thepinconfigurationofthe45117-segmentdriveranda7-segmentdisplayaregivenbelow.

1

4511

16

2 15

3 14

4 13

5 12

6 11

7 10

8 9

+2 to +6 V HC+5 V LS/HCToutput f

output g

output a

output b

output c

output d

output e

input B (2)

input C (4)

display test

blank output

blank input

input D (8)

input A (1)

0 V

g f Gnd a b

e d Gnd c dp

a

bf

g

ce

d

common cathode

Figure 7

Completethecircuitboarddiagrambelowthatcanconvertthemicrocontrollersignaltoa7-segmentdisplay.Althoughnotdesirable,asingleresistorhasbeenputinserieswiththedisplay.

input Ainput Binput Cinput D


END OF SECTION B

Question 19 (5marks)Emergingtechnologiesincludemotorvehiclesthatareconsideredtobelow-orno-emissionvehicles.Theseincludethefollowing.

Type 1: Hybrid Ahybridispoweredbyasmallerthannormalinternalcombustionengine.Extrapowerisprovidedbyanelectricmotorthatissuppliedbyabatteryforstop-startcitydrivingandacceleration.Thisvehicleisconsideredtobealow-emissionvehicleandhasarangesimilartoconventionalvehicles.

Type 2: Rechargeable batteryAnothertypeisavehiclepoweredentirelybyanelectricmotorthatissuppliedfromabatteryandhasarangeof80–100km.Thebatterycanberechargedfrommainselectricity,thereforeemittingnoemissionsfromthevehicleinoperation.Thevehiclealsocontainsanengine-poweredgeneratorthat,whenactivated,canextendtherangemuchfurtherbyrechargingthebatterywhilebeingdriven.Thevehicleisalsoconsideredtobelow-emissionwheninthe‘enginechargingthebattery’mode.

Type 3: Mains-only rechargeable batteryAthirdvehicleonthemarketisanelectricvehiclethatispoweredentirelybyanelectricmotorthatissuppliedfromalargerbatterythatgivesitarangeofapproximately150km.Thebatterycanberechargedonlyfrommainselectricity,thereforeemittingnoemissionsfromthevehicleinoperation.

Analysetheadvantagesanddisadvantagesofusingeachtypeofmotorinacityenvironment.


END OF QUESTION AND ANSWER BOOK

Gearratiofinal=gearratio1×gearratio2

Efficiency = output energyinput energy

× 100%

Voltage=current×resistance

Resistorsinparallel:Rt=R RR R

1 2

1 2

×

+

ColourcodesColour Valueblack 0brown 1red 2orange 3yellow 4green 5blue 6violet 7grey 8white 9gold 5%silver 10%

Resistorsinseries:Rt=R1 +R2

Power=voltage×current

Areaofcircle=�r2 (�=3.14)

Circumferenceofcircle=2�r

Force=pressure×area

gear A rpmgear B rpm

number of teeth gear Bnumber of teeth

= gear A

pulley A rpmpulley B rpm

radius of pulley Bradius of pulle

=yy A

Speed = distancetime

Gear ratio = number of teeth on driven gearnumber of teeth on driver gear

Mechanical advantage loadeffort

=

Torque=force×distance

Frequency = 1period

EfficiencyTotal=Efficiency1×Efficiency2

Formula sheet


Answers to multiple-choice questions

Question Answer

1 C

2 D

3 B

4 B

5 D

6 C

7 C

8 D

9 A

10 C

11 B

12 A

13 D

14 C

15 C

16 C

17 A

18 C

19 B

20 B

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