Name:___________________________ Instructor:____________Section:__________

ENGR 121 - Exam 2February 19, 2019

Allowed Materials: F.E. approved calculator(s) see syllabus; pencils and/or pens. ExamForm 11.

Honor Statement: On my honor, I promise that I have not received any unauthorized assistance on this exam (I didn’tlook at another student’s paper, I didn’t view any unauthorized written materials, I didn’t talk or listen to another student, Ididn't use an unauthorized calculator, I didn't use any electronic device, any visual or auditory signals, or any othertechniques of exchanging information with others.) I have maintained the highest standards of academic integrity whilecompleting this exam.

Signed:______________________________________________________________

Notes:If your last name is too long, just write the first 10 letters."F.I." and "M.I." are your first and middle initials, respectivelyYour "Username" is the first part of your LATech email addressFor "Section" use the guide provided to the rightYour "Exam Form" is printed on the upper right corner of this page.Indicate your major under "Major" section

Bubble: For Course Section:91 H01 - Easley TR 8-9:5092 H02 - Reis TR 2-3:5093 H03 - Swanbom MW 2-3:5094 H04 - Harbour MW 10-11:5095 H05 - Caldorera-Moore MW 8-9:5096 H06 - Gill TR 12-1:5001 001 - Pathak MW 8-9:5002 002 - Gill MW 10-11:5003 003 - Borquist TR 10-11:5004 004 - Hartmann TR 12-1:5005 005 - Borquist MW 12-1:5006 006 - Reis TR 4-5:5007 007 - Corbett TR 2-3:50

_____________________________________________________________________________________________________

1. (2 point deduction for failure to complete this problem!)Write in all of the indicated information in the boxes of your response form.Darken the appropriate circles to encode the corresponding information.Write your name on this exam and sign the Honor Statement.

Choices"A"

"B"

"I properly completed all required items in problem 1, so I will not lose these points"

"I did not properly complete problem 1 because I am fine with losing these points."

2. (3 points) The data type that should be used for thevariables which are displayed as the current temperatureand salinity values on the LCD screen is:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"char"

"float"

"long"

"byte"

"int"

"those variables do not need a data type"

"boolean"

3. (3 points) For the following circuit and Arduino sketch, as the temperature ________, the resistance ofthe thermistor ________, and the analog value ________.

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"increases, increases, increases"

"decreases, remains constant, increases"

"remains constant, increases, decreases"

"increases, decreases, increases"

"decreases, decreases, increases"

"increases, decreases, decreases"

"decreases, increases, remains constant"

2

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"Using tap water should not affect the sensor reading"

"Tap water often contains additional dissolved ions"

"Tap water has a high density value"

"DI water has a similar resistivity to tap water"

"Tap water will not corrode the probes over time"

"Tap water flushed through the sensor removes all salt"

"Tap water is free of extra dissolved ions"

"Electrical resistivity of tap water is very stable"

5. (3 points) The following equation was usedto convert analog values into salinity values:

This line of code, when written properly intoan Arduino sketch should be:

salinty 3.592 1022

val6.9134

=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"float salinity = pow(3.592, -22)*pow(val, 6.9134);"

"float val = 3.592*pow(10, -22)*pow(salinity, 6.9134);"

"float salinity = 3.592*(10, -22)*(val, 6.9134);"

"float salinity = 3.592*10power(-22)*valpower(6.9134);"

"long salinity = 3.592*e(10, -22)*e(val, 6.9134);"

"float salinity = 3.592*pow(10, -22)*pow(val, 6.9134);"

"int salinity = 3.592*pow(10, -22)*pow(val, 6.9134);"

"float salinity = 3.592*pow(-22)*val(6.9134);"

Note: assume val was previously defined inthe sketch as an int.

6. (3 points) In both simple and intelligent control techniques,the difference between the instantaneous value of the salinityand the setpoint is known as:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"error"

"deadband"

"gain"

"LCL"

"hysteresis"

"standard deviation"

"UCL"

"deadtime compensation"

7. (3 points) The operator used to ensure multiple conditional statements weretrue before executing a portion of the sketch is:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"&&"

"&="

"++"

"||"

"!"

"- -"

"-="

4. (3 points) A group calibrated their conductivity sensor using tap water, and now the sensor is reading odd values. Areason for the erroneous values is:

3

8. (3 points) The response of the system(the time each solenoid valve is left open)is ____________ the error.

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"inversely proportional to"

"unrelated to"

"three times"

"proportional to"

"the same as"

"plus or minus three times the standard deviation of"

"a fraction of the standard deviation of"

"independent of"

9. (3 points) In an intelligent control scheme, the ______ is a proportionality constant related to the amount of error being corrected by a single system response.

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"error"

"LCL"

"deadtime compensation"

"hysteresis"

"gain"

"UCL"

"deadband"

"standard deviation"

10. (3 points) The following information is known about a group's fishtank intelligent control system. If it has been 8seconds since the solenoid valve dropped DI water into the system and the current error reading is 27 analog values,then the salinity control portion of the system is:

Salinity Setpoint = 0.09% NaClAnalog Salinity Setpoint = 503Deadband = 48 Analog valuesDeadtime Compensation = 13 seconds

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"It is impossible to know what the system is doing with the given information"

"continually checking the salinity but waiting at least 5 more seconds before adjusting the salinity"

"dropping 1% NaCl water into the system"

"in a delay doing nothing for 5 more seconds before adjusting the salinity"

"dropping DI water into the system"

"is waiting to get a temperature reading before adjusting salinity"

4

11. (3 points) The following information is known about a group's fishtank intelligent control system. If the current salinityreading in analog is 475, 6 seconds since the last addition of salty water has passed, and the current temperature valuein analog is 480, then the temperature control portion of the system will have:

Salinity Setpoint = 0.09% NaClAnalog Salinity Setpoint = 503Salinity Deadband = 48 Analog valuesDeadtime Compensation = 13 seconds

Temperature Setpoint = 23degCAnalog Temperature Setpoint = 484Temperature UCL = 487Temperature Deadband = 6 Analog values

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"the heater off"

"DI water drop to warm the reservoir water"

"the system wait for the salinity to be corrected before doing anything with the

heater" "the heater on"

"the system stuck in a delay doing nothing for 7 more seconds"

"the heater oscillating on and off"

"not enough information to determine what the temperature control would be doing"

"the heater waiting for the deadtime compensation to pass before doing anything"

12. (5 points) Your fish tank has a volume 0.044 m3

of 0.15 wt% salt water and has aninitial temperature 19 degC . You would like to heat the water up to a temperature of 21degCusing your 20Ω heater connected to your 12V power supply. The time you need to leave theheater on to raise the temperature of the water to the desired temperature is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

13.3

14.2

15.1

15.9

16.8

17.6

18.5

19.4

hr

13. (5 points) A mixture of two materials has a mass 5.1kg . The mixture'stemperature increases by 11.2 degC over 2.5 minutes as the mixture

absorbs 101.2W of power. If the mass of material 1 is equal to 1.2kg , and

the specific heat of material 1 is Cp1 247.1J

kg degC , then the specific heat of

material 2 is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

205.3

222.2

238.5

255.0

271.5

288.0

304.5

320.9

J

kg degC

5

14. (5 points) During the cold winter months in Ruston, Dr. Harbour likes to enjoy a warm glass of chocolate milk before going to bed. His wife insists he use skim milk along with the chocolate syrup. He heats the beverage to a suitable temperature using a voltage source and a resistor (he is an EE after all!). If Dr. Harbour mixes skim milk =16.51⋅oz withchocolate syrup 5.01 oz , and heats his beverage from Tempinitial 33.1 degF to

Tempfinal 53.1 degF using a voltage source of 12V and a resistor value of value 12Ω ,

then the time Dr. Harbour has to wait to drink his beverage is closest to: Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

30.27

32.06

33.88

35.69

37.5

39.31

41.12

42.93

44.73

46.51

min

CpskimMilk 3977.5J

kg degC densityskimMilk 1.036

kg

L Conversion: 33.814 oz / 1 L

Cpchocolate 1600J

kg degC densitychocolate 1.268

kg

L

15. (5 points) You decide to try curing some ham with a brine solution. If you pour 2.73Lof water into a container, the amount of salt needed to produce your desired 22% brine isclosest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

0.57

0.61

0.65

0.69

0.73

0.77

0.81

0.85

kg

6

16. (5 points) The circuit shown below uses aconductivity sensor as discussed in this course. Ifthe voltage across the 10kΩ resistor is 1.85V ,then the number of H2 molecules that are formed

in 30 seconds is closes to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

1.21 1016

1.38 1016

1.56 1016

1.73 1016

1.91 1016

2.08 1016

2.25 1016

2.43 1016

H2molecules

17. (5 points) If 2.773(10)17 Cl2 gas molecules are formed over a time 15 s , then the

current passing through the probes of a conductivity sensor is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

5.56

5.93

6.29

6.64

7.00

7.37

7.72

8.08

mA

7

18. (5 points) Consider the conductivity sensor circuit shown. If the power dissipated by the10kΩ resistor is equal to to 0.526 mW , then the value returned by the analogRead functionis closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

327

351

373

398

421

445

469

493

517

540

19. (5 points) Two gallons of a salt water solution with a %wt NaCl 0.18 % is preparedby mixing water and NaCl. The amount of NaCl that should be added to this initialsolution such that the final solution contains 0.75 wt% NaCl is closest to:

Assume adding NaCl to water does not change the density of the salt solution in this case.

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

30.3

34.7

39.1

43.5

47.9

52.2

56.6

61.0

65.4

69.8

grams

8

20. (5 points) Assume you have a mass 3 kg of a salt water mixture that is 15% NaCl.You decide to mix in a certain amount of a 4% NaCl mixture to result in a total mixturethat is 12% NaCl. The amount of the 4% mixture that you must add is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

1.011

1.125

1.238

1.352

1.465

1.579

1.693

1.805

kg

21. (5 points) When Lonnie eats broccoli, he makes it bearable by applying a sauce that is 54 % mayonnaise and 46 % mustard. He begins preparing this recipe, but realizes he

has initially mixed 43 % mayonnaise with 57 % mustard, and he has 3 oz of thismixture. He wants to add enough mayonnaise to reach his preferred recipe. Once he does so,the mass of sauce he will have will be closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

3.04

3.27

3.49

3.72

3.94

4.17

4.39

4.62

4.85

5.07

oznote that all of the percentages given are by mass

9

22. (5 points)A solution of water and ethanol that is 7.1 % ethanol willbe heated in the setup shown so as to produce a more concentrateddistillate composed of 94 % ethanol and 6 % water. Before the

process starts, the heated vessel contains 456 grams of solution, and thedistillate vessel is empty. After the heat is removed (and all vaporizedwater and ethanol have drained into the respective vessels), the distillatevessel holds 29 grams of distillate solution. The new concentration ofethanol in the vessel that contained the initial solution is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

1.004

1.051

1.101

1.149

1.198

1.247

1.296

1.345

1.392

1.442

%

23. (5 points) A student's fish tank initially contains 58 grams of salt water that is 0.08% saltby weight. The target concentration for the salt water in the tank is 0.136 % . If 1% salt water

can be added at a rate of 0.17L

min , then the amount of time that the valve controlling the

flow of salt water should be open is closest to: Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

1.368

1.463

1.558

1.652

1.747

1.841

1.935

2.029

s

Assumptions:Any mass that is added, and equal amount of mass leaves through the drain.20% of the water leaving the tank through the drain has a concentration of the added 1%, andthe remainder has same concentration of the initial water in the tank.The density of water is constant at 1 kg/L, regardless of the weight percent of salt.

10

24. (5 points) Two freshman project groups have been runningtheir conductivity sensors for long periods of time, so long in

fact, that hydroxide (OH-) has built up significantly in theirsaltwater systems. (All of the chlorine and hydrogen gas thatmay have also been produced has vented to the atmosphereand dissipated.)

Both groups drain the water from their systems into acontainer, and the resulting mixture is 829 grams of solutionthat has concentrations listed under "Final Mix" in the tablebelow (by weight). The respective concentrations ofcomponents in the solution in Group B's system prior todraining is also given in the table, but only the saltconcentration is currently known for Group A's system. Theconcentration of hydroxide present in Group A's system priorto draining is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

0.0484

0.0527

0.0568

0.0610

0.0653

0.0695

0.0737

0.0780

0.0821

%

Note that all of the values given in the table are percentages!

concentrations

"" "Group A" "Group B" "Final Mix""Salt" 0.141 0.132 0.136

"Hydroxide" "unknown" 0.029 0.047

"Water" "unknown" 99.839 99.817

%

11

25. (5 points) Anna made an egg sandwich that consisted of the ingredients shown in the tablebelow. Given she used 2 servings of bread, the final mass of the sandwich was 148.7g, thefinal proportion of protein was 0.1167, and the final proportion of fat was proportion 0.2017 the serving size of egg that Anna put on the sandwich was closest to:

Bread Egg Mayonnaise Chedder Cheese

Serving Size 1 slice 1 large egg 1 tbsp 1 slice

Mass per Serving (grams) 30 50 13.8 28

Total Fat (grams) 1 5 10 9

Protein (grams) 2.7 6 0.1 7

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

0.46

0.52

0.57

0.63

0.69

0.74

0.80

0.86

12

26. (5 points) A distillation column at Gator Petrol Ltd. separates crude petroleum intovarious useful fuels and chemicals. The weight percentages of propane (P), gasoline(G), and diesel oil (D) for the inlet and the three outlets are shown below in thepicture. If the chemical plant must produce the product in the TOP outlet (which is

mostly propane) at a rate of 3600lb

hr , then the rate at which the feed stock must be

fed into the distillation column is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

6854

7595

8334

9095

9838

10589

11340

12086

lb

hr

Ptop 97 %

Gtop 2.3 %

Dtop 0.7 %

Pmid 12 %Pin 36 %

Gmid 82 %Gin 22 %

Dmid 6 %Din 42 %

Pbot 0 %

Gbot 1.4 %

Dbot 98.6 %

13

Bubble: For Course Section:91 H01 - Easley TR 8-9:5092 H02 - Reis TR 2-3:5093 H03 - Swanbom MW 2-3:5094 H04 - Harbour MW 10-11:5095 H05 - Caldorera-Moore MW 8-9:5096 H06 - Gill TR 12-1:5001 001 - Pathak MW 8-9:5002 002 - Gill MW 10-11:5003 003 - Borquist TR 10-11:5004 004 - Hartmann TR 12-1:5005 005 - Borquist MW 12-1:5006 006 - Reis TR 4-5:5007 007 - Corbett TR 2-3:50

ExamForm 11

While you are waiting to begin your test:

Please write and bubble your name and initials on your response sheet. If yourlast name is too long, just write the first 10 letters. "F.I." and "M.I." are your firstand middle initials, respectivelyPlease write and bubble your LATech username (e.g. abc567) on your responsesheet. Your "Username" is the first part of your LATech email addressPlease write and bubble your section number on your response sheet using theguide shown to the right.Please write and bubble your ExamForm number. ExamForm 11Indicate your major under "Major" section.

Also Note:

Mobile phones or other electronic devices (other than FE-approved calculators and plain timepieces) are not allowed onthis exam. If you have non-approved devices (including smartwatches), please deposit them at the front of the room forthe duration of the exam. Don't forget to retrieve them when you prepare to depart.Please deposit any bags you might have brought in the front of the room for the duration of the exam.There is a reference sheet given below.If you need additional scratch paper, please ask your proctor. Turn in any scratch paper with your exam, even if unused.If you have questions during the exam, please remain in your seat and raise your hand. A proctor will come to you.Please use a restroom now if you need it so as to minimize potential disruptions during the exam.

Reference Information:

1 Coulomb = 6.24(10)18 electrons Na = 23.0 g/mol

Avogardro's Number: 6.022(10)23 Cl = 35.5 g/mol

1in 25.4 mm C = 12.0 g/mol

H = 1.0 g/mol1ft 12 in1ton 2000 lb O = 16.0 g/mol

Vcylinderπ diameter

2

4height=

Vsphereπ6

= diameter3

14

ExamForm 11 192_ENGR121_E2February 19, 2019ind 1

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"A""B"

"D"

"B"

"F"

"A"

"A"

"D"

"E"

"B"

"D"

"B"

"E"

"D"

"F"

"D"

"B"

"G"

"D"

"B"

"D"

"E"

"C"

"F"

"G"

"F"