2014 poe final review.notebook · 2014 poe final review.notebook 1 may 27, 2014 may 2712:37 pm poe...

2014 POE FINAL REVIEW.notebook

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May 27, 2014

May 2712:37 PM

POE PART B THURSDAY 6/12

FINAL REVIEW

1. Design Process A problemsolving strategy used to develop a solutionA) Design Brief written information which contains problem statement, spec’s, and constraints.B) Brainstorming The process used to find a solution to a problem by collecting ideas C) Design Constraints Limitations and specifications the design must followD) Design/Decision Matrix TO HELP SELECT AN APPROACH, the matrix is developed to analyze the tradeoffs

12 STEPS OF DESIGN PROCESS

Prototype is a working, functional model

2. Computer Programming(RoboPro Flowchart)Open Loop- no feedbackclosed loop- has feedback

Digital- records 1 or 0ex. switches, phototransistor(light),

Analog- varies; records 0-5000ex. potentiometer, photoresistor (light)

3. Thermodynamics

4. Energy and PowerRenewable Resources- wind, solar, hydroNon-Renewable- coal, oil, uranium

Fuel Cell-is an electrochemical cell that converts chemical energy from a fuel into electric energy

-advantages are very quiet, renewable, -disadvantages are cost(expensive to produce large amounts of voltage) and no infrastructure in place.

Power= work/timeWork= Force*DistanceMoment= Force*Distance

U-Value-materials ability to conduct heat

R=1/u


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5. Fluid Power SystemsHydraulics- uses liquids to create powerPneumatics- uses gases to create power

Pressure within a fluid power systemis always increasing

6. ElectricityV=IRSeries(current stays the same)Parallel(voltage stays the same)

7. StaticsVectors- have magnitude and directionScalar- have magnitude but NO direction

Free Body Diagrams

Beam Deflection

Moment of Inertia

Centroid-an objects center of gravity

• is a mathematical property of a cross section (measured in inches 4) that is concerned with a surface area and how that area is distributed about a centroidal axis.

**CONVERT ALL UNITS TO INCHES


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8. MaterialsManufacturing Processes:Casting and Foundry in one step raw materials are transformed into a desirable shape Forming or MetalworkingMachiningJoining and AssemblyRapid Prototyping

Categories of Materials:• Metals and Alloys- Possess material properties including high strength and

toughness, high electrical conductance, high thermal conductance, luster• Polymers(ex. plastics)- • Thermosetting plastics are formable once

Thermoplastics can be heated repeatedly and formed into new shapes • Ceramics- Because of the strength of the bonding, ceramics have high melting temperatures

• Composites- 2 or more materials chemically combined

9. Materials TestingStrain- the amount of deformation or elongation(inches) within a test specimen

Modulus of Elasticity Formulas

**for a stress vs strain graph

**for a load vs displacement graph

Ductility Amount of plasticity before fracture. The greater the ductility, the more a material can be deformed.Brittle opposite of ductility


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10. Simple Machines, Pulleys, Gears

11. Kinematics

12. Statistics

Mr. Desantis hits a golf ball at a takeoff angle of 30 degrees and an initial velocity of 70 ft/sec

A) Find the initial horizontal velocity

B) What is the golf balls horizontal distance? Use 32.15ft/sec2 for acceleration due to gravity 30

Screws:

Circumference = 3.141(diameter)

Mean (average), Median (middle number), and mode (number that appears most often)2,2,4,5,6,10,13

MeanMedianMode

What is the probability a head will land on the toss of a coin?

A million dollar bill is flipped 3 times....what is the probability that desantis' face will appear on exactly 2 of the tosses?


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1. Figure 1 shows a small bolt cutter. A standard bolt is placed through the appropriate hole and the handle is squeezed to cut off the bolt.

Figure 1

a) A steel bolt with a diameter of 0.125in is being cut. What is the cross sectional area of the bolt?

b) The maximum shear stress for the steel in this bolt is 55,000 psi. What is the force needed to cut the bolt?

2. Your grades for the marking period in English are as follows:95,60,68,78,99,87,94,87,100,77,96

a) calculate the mean (round to the nearest tenth): _________ b) calculate the mode: __________c) calculate the median: __________ d) calculate the range: __________

3. A ¾ inch diameter aluminum dogbone is subjected to a tensile test. After the sample is broken, it was fitted back together. The distance between gauge points, originally 2.25 inches now measures 2.83 inches. What is the percent of elongation of the sample. Round to the nearest tenth.

Additional part 2 practice


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May 177:30 AM

a) The section of the graph from point A to point B is a relatively straight line. During this time the sample is said to be in what range or state? If the force were to be removed at any time during this section of the graph, what happens to the length of the sample?

b) What is happening to the sample, if anything, while the section of the graph from points C to D is being plotted? What clues do you have from the graph?

c) What happened to the sample at point D? How do you know? And calculate the stress at this point, given a final area of .006.

d) Assume the sample being tested here is mildly ductile. How would the graph differ, specifically in the section of the graph from points C to D, if you were testing a specimen of the exact same size and the sample was known to be HIGHLY ductile?

e) What does point C on the graph represent? And calculate the stress at this point, given a initial area of .008.

4. The graph below shows a typical ForceElongation graph from a sample broken on the Structural Stress Analyzer.


plastic def, neckingpiece broke


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May 177:35 AM

5. The closedloop program shown below is designed to send a shuttle back andforth between two points. Study the program description and decide whichof the program elements from the answer bank (A through J) must be used tocomplete the flowchart program. Write the letter of the correct icon in thecorresponding empty box. No icon will be used more than once, and somemay not be used at all. (8 points)Program Description:When the program starts, shuttle M1 is turned on in the clockwise direction,and the computer checks to see if limit switch I2 (wired normally open) isbeing pressed. The program will loop back until switch I2 is pressed. Fromthere, shuttle M1 will stop and then start again in the counterclockwisedirection. The computer will then loop back until switch I1 (wired normallyopen) is pressed. Once I1 has been pressed shuttle M1 stops. The programthen loops back to the beginning.

cw



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Additional part A practice6. calculate the moment of inertia for the beam to the right

7. calculate the beam deflection for the beam above if the load is 300lbs, length is 10'. assume the mod of elasticity is 2.8 x 10 6

4in

6in

8. solve for the angle of point B

9. what is the mechanical advantage for a screw with 2" diameter and 32 threads per inch

10. calculate the effort force needed to lift an object of 1000lbs using a moveable pulley

11. calculate the gear ratio for a driven gear of 50 teeth and a driver gear of 25 teeth

12. calculate the gear ratio if the speed of the output gear is 1000rpm's and the input gear is 200rpm's

B

A

C

9ft

5ft


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POE PART 2FINAL REVIEW

1. HEAT LOSS/GAIN

PROBLEM#1:A)CALCULATE THE HEAT LOSS THROUGH A WALL THAT IS 10ft X 10ft AND HAS A UVALUE OF .5 IF THE OUTSIDE TEMPERATURE IS 350F AND THE INSIDE TEMPERATURE IS 750F

B) WHAT IS THE RVALUE OF THE WALL?


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2. WORK, POWER, EFFICIENCY

Power= Voltage * Current

Mechanical Efficiency

the higher the efficiency, the more work is done

Eff %= (powerout/powerin) 100

PROBLEM #2:AN ELECTROMOTOR LIFTS A CAR A WEIGHT OF 40NEWTONS A DISTANCE OF 2 METERS IN 11 SECONDS. WHILE THE CAR WAS LIFTED, THE VOLTAGE WAS 24V AND THE CURRENT WAS .5A

A) FIND THE AMOUNT OF WORK DONE

B) FIND THE OUTPUT POWER

C) FIND THE INPUT POWER

D) FIND THE EFFICIENCY OF THE SYSTEM


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3. ELECTRICITY V=IR

PROBLEM #3


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4. GEAR RATIO

PROBLEM #4:THE COMPOUND GEAR TRAIN BELOW IS USED TO ROTATE AN AXLE. GEAR A HAS 20 TEETH, GEAR B HAS 10 TEETH, GEAR C HAS 15 TEETH, AND GEAR D HAS 12 TEETH

A) CALCULATE THE MECHANICAL ADVANTAGE OF THE GEAR TRAIN

B) IF GEAR A SPINS AT 25ORPM, HOW FAST WILL D SPIN


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5. FLUID POWER

PROBLEM #5:THE GAUGE PRESSURE OF A PNEUMATIC NEEDLE IS 100psi. WHEN THE VOLUME IS 4Oin3. A FORCE IS APPLIED TO THE CYLINDER CAUSING THE GAS TO COMPRESS. THE GAUGE NOW READS 200psi WITH AND ATMOSPHERIC PRESSURE IS 18psi

A) WHAT IS THE ABSOLUTE PRESSURE BEFORE AND AFTER THE CYLINDER GAS IS COMPRESSED?

B) ASSUMING THE TEMP IS CONSTANT, HOW MUCH GAS IS IN THE CYLINDER AFTER THE CYLINDER IS COMPRESSED


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6. COMPUTER PROGRAMMING


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7. DESIGN PROCESS


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8. TENSILE TESTING

PROBLEM#8:A TENSILE TEST WAS PERFORMED AND THE RESULTS WERE RECORDED ON THE GRAPH BELOW. THE LENGTH PRIOR TO TESTING WAS 2in AND THE AREA WAS 1.5in 2

A)CALCULATE YIELD POINT(PROPORTIONAL LIMIT) STRESS

B) CALCULATE ULTIMATE STRESS

C) CALCULATE MOD OF ELASTICITY


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9. TRUSS CALC'S & REACTION FORCES

RAX

RAY RBY

AB

C

D

100lbs 100lbs

3ft 6ft 3ft

4ft

500

PROBLEM #9:STUDY THE TRUSS ABOVE AND COMPLETE THE PROBLEMS

A) CALCULATE THE HEIGHT OF THE TRUSS

B) DRAW THE FREE BODY DIAGRAM FOR JOINT A AND CALCULATE Fac


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10. KINEMATICS

Mr. Desantis hits a golf ball at a takeoff angle of 30 degrees and an initial velocity of 70 ft/sec

A) Find the initial vertical velocity

B) What is the golf balls horizontal distance? Use 32.15ft/sec2 for acceleration due to gravity

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2014 poe final review.notebook · 2014 poe final review.notebook 1 may 27, 2014 may 2712:37 pm poe...

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