R=1/u. May 27, POE FINAL REVIEW.notebook

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B) Brainstorming The process used to find a solution to a problem by collecting ideas C) Design Constraints Limitations and specifications the design must follow D) Design/Decision Matrix TO HELP

1 POE PART B THURSDAY 6/12 FINAL REVIEW 1. Design Process A problem solving strategy used to develop a solution A) 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 follow D) Design/Decision Matrix TO HELP SELECT AN APPROACH, the matrix is developed to analyze the trade offs 12 STEPS OF DESIGN PROCESS 2. Computer Programming(RoboPro Flowchart) Open Loop- no feedback closed loop- has feedback Digital- records 1 or 0 ex. switches, phototransistor(light), Analog- varies; records ex. potentiometer, photoresistor (light) U-Value-materials ability to conduct heat Prototype is a working, functional model 3. Thermodynamics R=1/u 4. Energy and Power Renewable Resources- wind, solar, hydro Non-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 / time Work= Force*DistanceMoment= Force*Distance May 27 12:37 PM 1

5. Fluid Power Systems Hydraulics- uses liquids to create power Pneumatics- uses gases to create power

ElectricityV=IR Series(current stays the same)parallel(voltage stays the same) 7.

Moment of Inertia is a mathematical property of a cross section (measured in inches and how that area is

2 5. Fluid Power Systems Hydraulics- uses liquids to create power Pneumatics- uses gases to create power Pressure within a fluid power system is always increasing 6. ElectricityV=IR Series(current stays the same)parallel(voltage stays the same) 7. Statics Vectors- have magnitude and direction Scalar- have magnitude but NO direction Free Body Diagrams Moment of Inertia is a mathematical property of a cross section (measured in inches and how that area is distributed about a centroidal axis. 4) that is concerned with a surface area Beam Deflection Centroid -an objects center of gravity **CONVERT ALL UNITS TO INCHES May 31 7:40 AM 2

8. Materials Manufacturing Processes: Casting and Foundry in one step raw materials are transformed into a desirable shap Forming or Metalworking Machining Joining and Assembly Rapid Prototyping

3 8. Materials Manufacturing Processes: Casting and Foundry in one step raw materials are transformed into a desirable shap Forming or Metalworking Machining Joining and Assembly Rapid 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 Testing Strain- the amount of deformation or elongation(inches) within a test specimen Modulus of Elasticity Formulas **for a load vs displacement graph **for a stress vs strain graph Ductility Amount of plasticity before fracture. The greater the ductility, the more a materia can be deformed. Brittle opposite of ductility May 27 12:38 PM 3

10. Simple Machines, Pulleys, Gears Screws:

of 30 degrees and an initial velocity of 70

B) What is the golf balls horizontal distance?

15ft/sec 2 for acceleration due to gravity 30

number), and mode (number that appears most

the probability a head will land on the toss of

4 10. Simple Machines, Pulleys, Gears Screws: Circumference = 3.141(diameter) 11. Kinematics Mr. Desantis hits a golf ball at a take off 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/sec 2 for acceleration due to gravity Statistics Mean (average), Median (middle number), and mode (number that appears most often) 2,2,4,5,6,10,13 Mean Median Mode 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 wi appear on exactly 2 of the tosses? May 31 9:37 AM 4

5 Additional part 2 practice 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 in 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. May 17 7:28 AM 5

6 Additional part 2 practice 4. The graph below shows a typical Force Elongation graph from a sample broken on the Structural Stress Analyzer. 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? plastic def, necking 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. piece broke 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 o 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. May 17 7:30 AM 6

7 Additional part 7 practice 5. The closed loop program shown below is designed to send a shuttle back andforth between two points. Study the program description and decide which of the program elements from the answer bank (A through J) must be used to complete the flowchart program. Write the letter of the correct icon in the corresponding empty box. No icon will be used more than once, and some may 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) is being pressed. The program will loop back until switch I2 is pressed. From there, shuttle M1 will stop and then start again in the counter clockwise direction. The computer will then loop back until switch I1 (wired normally open) is pressed. Once I1 has been pressed shuttle M1 stops. The program then loops back to the beginning. cw May 17 7:35 AM 7

8 Additional part A practice 6. calculate the moment of inertia for the beam to the right 4in 6in 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 solve for the angle of point B 9ft A B 5ft C 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 May 17 8:56 AM 8

9 POE PART 2 FINAL REVIEW 1. HEAT LOSS/GAIN PROBLEM#1: A)CALCULATE THE HEAT LOSS THROUGH A WALL THAT IS 10ft X 10ft AND HAS A U VALUE OF.5 IF THE OUTSIDE TEMPERATURE IS 35 0 F AND THE INSIDE TEMPERATURE IS 75 0 F B) WHAT IS THE R VALUE OF THE WALL? May 25 7:44 AM 9

2. WORK, POWER, EFFICIENCY Mechanical Efficiency the higher the efficiency,

100 PROBLEM #2: AN ELECTROMOTOR LIFTS A CAR A WEIGHT OF 40NEWTONS A DISTANCE

WHILE THE CAR WAS LIFTED, THE VOLTAGE WAS 24V AND THE CURRENT WAS.

10 2. WORK, POWER, EFFICIENCY Mechanical Efficiency the higher the efficiency, the more work is done Power= Voltage * Current Eff %= (power out /power in ) 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 C) FIND THE INPUT POWER B) FIND THE OUTPUT POWER D) FIND THE EFFICIENCY OF THE SYSTEM May 25 7:51 AM 10

11 3. ELECTRICITY V=IR PROBLEM #3 May 25 8:03 AM 11

12 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 May 25 9:55 AM 12

THE GAUGE NOW READS 200psi WITH AND ATMOSPHERIC PRESSURE IS 18psi A) WHAT IS THE ABSOLUTE PRESSURE BEFORE

13 5. FLUID POWER PROBLEM #5: THE GAUGE PRESSURE OF A PNEUMATIC NEEDLE IS 100psi. WHEN THE VOLUME IS 4Oin 3. 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 May 25 10:05 AM 13

14 6. COMPUTER PROGRAMMING May 25 10:23 AM 14

15 7. DESIGN PROCESS May 25 10:25 AM 15

16 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 May 25 10:28 AM 16

17 9. TRUSS CALC'S & REACTION FORCES 100lbs 100lbs C 4ft R AX A D 50 0 B R AY 3ft 6ft 3ft R BY 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 F ac May 25 12:51 PM 17

18 10. KINEMATICS Mr. Desantis hits a golf ball at a take off angle of 30 degrees and an initial velocity of 70 ft/sec 30 A) Find the initial vertical velocity B) What is the golf balls horizontal distance? Use 32.15ft/sec 2 for acceleration due to gravity May 25 12:51 PM 18

Principles Of Engineering. Part A

Principles Of Engineering. Part A Principles Of Engineering Final Examination Part A Fall 2007 Student Name: Date: Class Period: Total Points: /40 Converted Score: /50 Page 1 of 11 Directions: Circle the letter of the response that best