Name:___________________________ Instructor:____________Section:__________

ENGR 122 - Exam 1April 14, 2015

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’t look

at another student’s paper, I didn’t view any unauthorized written materials, I didn’t talk or listen to another student, I didn't use

an unauthorized calculator, I didn't use any electronic device, any visual or auditory signals, or any other techniques of

exchanging information with others.) I have maintained the highest standards of academic integrity while completing this

exam.

Signed:______________________________________________________________

Instructions: Encode your answer to each question by darkening the appropriate circle on your response form. You are also

encouraged to work neatly and circle your chosen answers on the exam document so that you are better able to review your

work if you find the need. However, the answers you encode on the response form will be taken as your definitive answers,

and the entire basis for your grade. Please review your response form carefully before submission.

For Course Section:

H01 - Crittenden TR 10-11:50

H02 - Reeves TR 2-3:50

H03 - Swanbom TR 12-1:50

H04 - Hall TR 8-9:50

H05 - Evans MW 8-9:50

001 - Swanbom MW 2-3:50

002 - Moller TR 12-1:50

003 - Moller TR 8-9:50

004 - Easley TR 2-3:50

wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww

1. (2 point deduction for failure to complete this problem!)wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww

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.•

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, respectively•Your "Username" is the first part of your LATech email address•For "Section" use the guide provided to the right•Your "Exam Form" is printed on the upper right corner of this•page.

Indicate "ENGR" as the "Program"•

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 PING))) sensor discussed in class operates

by emitting and receiving:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"x-rays"

"gamma rays"

"radio frequency signals"

"ultrasonic pressure waves"

"infrared pulses"

"infrasonic pressure waves"

"laser signals"

"ultraviolet light"

=

3. (3 points) When using an

infrared emitter anddetector with the Arduino,the IR LED is set to pulse at38kHz. What is the mostimportant reason for thispulsing?

Choices

"A"

"B"

"C"

"D"

"E"

"In order to help filter out other sources of IR radiation"

"In order to draw less power by turning the IR LED off every now and then"

"IR LEDs will burn out if not pulsed at 38kHz"

"Any LED attached to an Arduino pulse at this rate by default"

"To increase the range of the IR LED"

=

Bubble:

91

92

93

94

95

01

02

03

04

2

4. (3 points) In The Ten Faces of Innovation which persona is

associated with the motto of "Fail Often to Succeed Sooner":

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"Collaborator"

"Set Designer"

"Experimenter"

"Anthropologist"

"Experience Architect"

"Hurdler"

"Director"

"Cross-Pollinator"

=

5. (3 points) When using sheet metal, what tool is best suited for

bending the sheet metal to a specific angle?

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"rivets"

"sheet metal brake"

"hand shear"

"vise grips"

"sheet metal punch"

"sheet metal roller"

"sheet metal shear"

"a claw hammer"

=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"Brainstorming method"

"Pugh method"

"Design Thinking Method"

"Deep Dive method"

"Concept Chooser method"

"Mind Map method"

"Innovation Method"

"Creative Control method"

"Painstorming method"

=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"to make it possible to center the servos"

"to prevent backlash at the output shaft "

"to make it possible for the output shaft to turn at different speeds"

"to change the direction of the output shaft's rotation"

"to lower the amount of energy lost in the output shaft"

"to raise the amount of friction applied to the output shaft"

"to increase the torque at the output shaft, and decrease the rotational speed of the output shaft"

"to increase the rotational speed of the output shaft, and decrease the torque at the output shaft"

=

6. (3 points) The method discussed in class to use when deciding

between multiple design conepts is the:

7. (3 points) Inside your servos on your bot, there are several plastic gears. What is the primary purpose of this "gear train"?

3

8. (3 points) The most correct

statement about the ADXL335Accelerometer is (wrt is short for"with respect to"):

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"can be used to measure the angle of an object wrt 3-axes"

"is used to make hi-speed servos"

"can be used to measure the position of an object in a 3-axis coordinate system"

"can ONLY be used to measure the tilt of an object wrt 3-axes"

"requires a 38kHz signal in order to operate"

"produces a resistance measurement that must be calibrated"

"can only be used to measure the angle of an object wrt 1-axis"

"only works wrt polar coordinate system"

=

9. (3 points) The diagram shown here is best classified as a:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"stream-of-consciousness map"

"concept map"

"thought diagram map"

"brain storming map"

"thought map"

"mind map"

"Pugh map"

"bug map"

=

10. (3 points) Given the gear train shown below where Gears B and

C are stacked together and Driver gear A rotates at 10 RPM, whichgear(s) is/are rotating at the highest RPM:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"Driver gear A"

"Gears B and C"

"Gear A and Driven gear D"

"Gears A and B"

"Driven gear D"

"Gear B"

"they are all at the same RPM"

"Gear C"

=

11. (3 points) The items shown here are called:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"Stacks"

"Wrist Pins"

"Rivets"

"Bolts"

"Screws"

"Pop Pins"

"Bevels"

"Nail Pins"

=

4

12. (5 points) The x-component

of the force depicted here isclosest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

396.5

169.0−

441.4−

396.5−

362.5−

441.4

362.5

52.9−

52.9

169.0

N⋅=

F 400 N=

θ 25 deg⋅=

13. (5 points) The magnitude of the resultant of

the two forces depicted here is closest to:

F1 1.6 kN⋅=

θ1 30 deg⋅=Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

3.387

0.128

0.622

1.957

2.787

0.000

0.357

0.364

2.608

3.400

kN⋅=F2 1.8 kN⋅=

θ2 50 deg⋅=

14. (5 points) The resultant of the

two forces given forms an anglerelative to the x axis that isclosest to:

Rx 150 N=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

61.93

30.56

28.07

0.56

1.08

57.77

0.49

32.23

0.00

1.01

deg⋅=Ry 80 N=

5

15. (5 points) You decide to hang some art in your dorm room. Using unequal lengths of rope to hang the art (weight

of art is Wart 8 lbf⋅= ), you (and your level and protractor) have determined the angles to be as shown below. The

force in the rope attached to point A is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

5.17

5.56

5.97

6.37

6.78

7.18

7.59

8.00

8.41

8.81

lbf⋅=

Wart 8 lbf⋅= θ 32 deg⋅= ϕ 26 deg⋅=

Note: The drawing is not to scale.

16. (5 points) A barrel rests in a rack as shown. A force sensor is

placed at B and indicates that the force at B is FB 120 lbf⋅= . For

the angles and force given, the weight of the barrel is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

368.7

391.9

415.2

438.5

462.0

485.4

508.9

532.0

556.0

578.9

lbf⋅=ϕ 13 deg⋅= θ 47 deg⋅= FB 120 lbf⋅=

Note: The drawing is not to scale.

6

17. (5 points) A force F is applied to the end of a lever. If the lever makes an

angle of θ with the horizontal axis, then the moment about point A is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

15.8

17.0

18.1

19.3

20.5

21.7

22.8

24.0

N m⋅⋅=

Note: The drawing is not to scale.

F 10 N= θ 15 deg⋅=

18. (5 points) A carpenter is using the crowbar to pull a nail. If the nail requires the

given force to be extracted, what push P will the carpenter need to apply to the endof the crowbar?

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

109.4

118.9

128.4

138.0

147.6

157.1

166.7

176.2

N=

Note: The drawing is not to scale.

Fnail 550 N= a 12 cm⋅= b 42 cm⋅=

7

19&20. A worker has hooked a tractor to a goal post using a rope

as shown. The tension in this rope is 500 lb when the tractor pulls. Aweight W is also hung from the goal post as shown. The combinedmoment due to the rope and the weight, about the bottom of the post(defined by point A) is closest to:

Note: The drawing is not to scale.

W 200 lbf⋅= d1 40 in⋅= d2 10 in⋅=

Problem 19 (4 points):

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

5890

6303

6709

7115

7523

7931

8339

8744

ft lbf⋅⋅=

Problem 20 (1 point):

Choices"Clockwise"

"Counter-clockwise"

=

8

21. (5 points) Captain Jack Sparrow has managed to grab a root

with his left hand and a rope connected to the roasting pole with hisright hand before plunging to his demise at the bottom of the ravine.One end of the roasting pole has caught on one side of the ravine,so that the wall prevents motion both vertically and horizontally. Theother end of the pole rests on the muddy bank at the top of theravine's other side. Jack's right hand is pulling on the rope with theforce given below. Based on the dimensions given, determine theforce exerted on the pole by the muddy bank. Assume that the mudis so slippery that friction is insignificant, and assume that the weightof the pole is insignificant.

Note: The drawing is not to scale.

Frope 160 lbf⋅= a 10 ft⋅= b 2.4 ft⋅=Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

26.9

28.7

30.6

32.4

34.3

36.1

38.0

39.8

lbf⋅=c 2.1 ft⋅= ϕ 12 deg⋅= θ 41.186 deg⋅=

9

22. (5 points) Angular velocity data for each of the gears shown is

given below. If a torque 9 in lbf⋅⋅= must be driven at gear A, the

torque that must be applied to gear C is closest to:

ωA 1600 rpm⋅=

ωB 1070 rpm⋅=

ωC 530 rpm⋅=

ωD 650 rpm⋅=Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

4.64

2.98

3.66

4.46

17.45

22.15

27.17

13.46

18.17

6.02

in lbf⋅⋅=ωE 825 rpm⋅=

Note: assume frictionless bearings and lossless gears.

23 & 24. The numbers of teeth on each of the gears shown are given below. If gear 1 is

turned at an angular speed 1230 rpm⋅= clockwise, then the speed of gear 6 is closest to:

Problem 25: (4 points) Problem 26: (1 point)

Choices"A"

"B"

"clockwise"

"counter-clockwise"

=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

1450.9

1269.7

56.6

2967.4

2539.4

244.6

595.8

141.1

1230.0

10723.6

rpm⋅=N1 31 teeth⋅= N2 93 teeth⋅=

N3 29 teeth⋅= N4 133 teeth⋅=

N5 101 teeth⋅= N6 64 teeth⋅=

10

25. (5 points) A DC electric motor draws 1 amp of current at 12 volts. If a mass of 10 kg is lifted "h" meters over "t" seconds,

then the efficiency of the motor is closest to:

h 10 m= t 160 s=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

35.6

38.6

41.7

44.9

48.0

51.1

54.2

57.3

%⋅=

26. (5 points) A DC electric motor whose output shaft is spinning at 20 RPM

lifts a weight of 10 kN vertically while being wound up on a pulley with adiameter of d. If the large gear has N teeth and the efficiency of the motor is80%, then the electric power delivered to the motor is closest to:

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

6.1

6.5

6.9

7.3

7.7

8.1

8.5

8.9

kW⋅=

d 1 m= N 20=

11

27. (5 points) A diagram showing the mechanics of an alligator's

lower leg is shown. The ground applies a force of F 75 lbf⋅= to the

alligator's foot, at an angle of ϕ 81 deg⋅= . The x, y coordinates of

this point of contact with the ground are given below. The y' axis isaligned with the tibia and fibula bones, as well as the axis of theachilles tendon. Assuming the ankle acts as a frictionless pinrotating at the origin, the force carried in the achilles tendon(indicated by Ttendon) is closest to:

coordinates of point of contact:

x y( ) 2.5− 5.1−( ) in⋅=

θ 19 deg⋅=

Choices

"A"

"B"

"C"

"D"

"E"

"F"

"G"

"H"

"I"

"J"

239.48

442.72

152.44

73.74

17.25

110.29

144.13

108.94

222.23

225.00

lbf⋅= a 1.7 in⋅=

12

ExamForm 11=

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.•

Bubble:

91

92

93

94

95

01

02

03

04

For Course Section:

H01 - Crittenden TR 10-11:50

H02 - Reeves TR 2-3:50

H03 - Swanbom TR 12-1:50

H04 - Hall TR 8-9:50

H05 - Evans MW 8-9:50

001 - Swanbom MW 2-3:50

002 - Moller TR 12-1:50

003 - Moller TR 8-9:50

004 - Easley TR 2-3:50

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, respectively•Your "Username" is the first part of your LATech email address•For "Section" use the guide provided to the right•Your "Exam Form" is printed on the upper right corner of this•page.

Indicate "ENGR" as the "Program"•

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."

=

13

ExamForm 11=

Key

1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

"A"

"D"

"A"

"C"

"B"

"B"

"G"

"A"

"F"

"A"

"C"

"E"

"G"

"C"

"H"

"E"

"D"

"F"

"C"

"A"

"C"

"G"

"H"

"B"

"F"

"B"

"G"

=