Maintains Systems and Works with Existing Products

Principles of EngineeringName:

Semester 1 Final Review

1. Describe the duties of an engineering technologist.

Maintains systems and works with existing products.

1. Give 5 characteristics of an engineering notebook.

1.Pages are sequentially numbered in ink on top outside edge. 2. Notebooks are bound. 3. No pages are removed from the notebook for any reason. 4. All figures and calculations are clearly labeled. 5. The notebook is stored in a safe location when it is not being used. 6. Each page is signed & dated before the next page is begun. 7. When the notebook is full, a new one begins & picks up where other ended. Archive the old notebook. 8. Entries start at the top of the page, working left-to-right & top-to-bottom. 9. Markers that bleed through the paper are not used. 10. Inserted items are permanently attached. Loose leaf items do not belong in the notebook. 11. The date that each entry was made is clearly indicated. 12. Mistakes are crossed off, initialed, with correction placed nearby. Never erase or remove anything. 13. Consistent recording methods for ideas, references, test results, etc. are used throughout the notebook. 14. A colleague or mentor should corroborate the events and facts on each page and sign off as a witness in the appropriate situation.

1. Draw and describe the following levers:
2. First-class – fulcrum between load and effort – example see saw

1. Second-class – load between fulcrum and effort – example wheel barrow

1. Third-class – effort between fulcrum and load - shovel

1. In a second-class lever, describe the relationship between effort arm and the load (resistance) arm.

MA = LE/LL, mechanical advantage is always greater than 1

1. The wheels on a bicycle have a 10” radius. Assuming no sliding or slipping between the wheel and the road, how far will the bicycle travel for every one

full revolution of the wheels?

C = 2πr=(2)(3.14)(10) = 62.8 inches

1. A ramp is used to raise an object 3’ from the ground. The lengths of the sides of the ramp are shown in the figure below. What is the mechanical advantage

of the ramp?

MA = 10.44/3=3.48

1. What are the 6 simple machines?

Lever, wheel & axle, pulley, inclined plane, wedge, screw

1. a. Given the pulley configuration below, how many pounds of effort force would a user have to exert on the rope to lift the 60 lb. load?

9.

a. What class of lever is shown in Figure 5? Justify your answer.

First class, fulcrum is between load and effort

b. If a 50 lb effort is needed to balance a 260 lb load, how far from the fulcrum should the load be located? (answer precision = 0.0)

MA=DE/DR 52/x = 260/50 x = 10 in

c. What is the IMA?

Ideal Mechanical Advantage:Theory-based calculation IMA=52/10=5.2

Friction loss is not taken into consideration

Ratio of distance traveled by effort and resistance force

d. What is the AMA?

Actual Mechanical Advantage:Inquiry-based calculationAMA=260/50=5.2

Frictional losses are taken into consideration

Used in efficiency calculations

Ratio of force magnitudes

e. What is the efficiency?

In a machine, the ratio of useful energy output to the total energy input, or the percentage of the work input that is converted to work output

The ratio of AMA to IMA

EFF=AMA/IMA=5.2/5.2

Use the figure below to answer questions 10 – 12. The wrench used to turn the screw is 6 in long.

¼ 15 NC

13. Pulley Problems:

Solve for the unknown quantities in problems 1 through 5. Show all your work. List the equations used and units for your answers.

1. Gear Problems:

Solve for the unknown quantities in problems 1 through 5. Show all your work. List the equations used and units for your answers.

1. Give a brief description of each of the following engineering fields.

Aerospace:

Design, develop, and test aircraft & spacecraft ranging from rockets and spacecraft to gliders and small passenger aircraft

Agricultural:

Create technology to advance food, biological, irrigation, and machinery systems

Biomedical:

Devise procedures and devices to improve medical conditions

Chemical:

Address issues related to chemical production, transformation of raw materials, and chemical use

Civil:

Plan the design, construction, and maintenance of various civil structures

Computer Hardware:

Research, design, and test computer systems and computer-related equipment

Electrical:

Design, develop, and test the manufacture of electrical equipment and large-scale electrical equipment

Electronics:

Design, develop, and test small electronic systems, such as appliances, telephones, surgical devices, etc.

Environmental:

Solve environmental problems related to pollution, water use, materials and energy use, waste treatment, etc.

Health and Safety:

Identify potential hazards and develop protocols to prevent or reduce hazardous situations

Industrial:

Plan the most effective, efficient ways to build structures, lay out production facilities, run organizations, transport goods, etc.

Marine and Ocean:

Design, construct, operate, and maintain machinery or structures that exist in or near the water

Materials:

Develop, process, & test materials to be used to fulfill a specific design purpose

Mechanical:

Research, develop, manufacture, & maintain devices that produce or consume power

Mining and Geological:

Design, develop, & maintain mines, mining equipment, & mining techniques needed to locate & extract ores from the Earth

Nuclear:

Develop methods and systems that utilize nuclear materials for energy, medicine, and industry

Petroleum:

Locate oil or natural gas reservoirs and design methods to extract and transport oil

1. Sketch a series circuit.

1. Sketch a parallel circuit with 2 paths.

1. In a series circuit:

1. In a parallel circuit:

IT= I1+ I2

1. Find the total resistance and current for the circuit below.

1. Find the current through R1 (IR1), R2 (IR2), and R3 (IR3) for the following circuit:

1. Describe how to use a multimeter to measure current, resistance and voltage.

Current wire the meter into the circuit,

resistance remove power and place meter probes on any side of the resistor,

voltage place probes on the circuit

1. Give 3 examples of nonrenewable energy sources.

Coal, oil, natural gas, uranium

1. Give 3 examples of renewable energy sources.

Animals, food, biomass

1. What is a Joule?

The base unit for work = Nm

1. What is a Watt?

The base unit of power=J/s

1. What is kilowatt-hours?

The unit in which we buy electricity

1. a) A mover pushes a 40 N box along the floor to a door 5 m away. Calculate the work done by the mover.

W=Fd=(40N)(5m)=200Nm

b) If the mover moved the box in 4 seconds, how many Watts of power are used to move the box?

Power=W/t=200Nm/4sec=50W

1. What is the Conservation of Energy:

Energy cannot be created or destroyed, but it can change from one form to another

1. Name three examples of energy transformation.

Chemical, radiant, and electrical

1. Define the following methods of heat transfer and give an example of each:
2. convection – the transfer of thermal energy by movement of fluid (liquid or gas)

1. conduction –the transfer of thermal energy within an object or between objects from molecule to molecule

1. radiation – the process by which energy is transmitted through a medium, including empty space, as electromagnetic waves

1. What is the relationship of the U-value and the R-value?

They are reciprocals

1. What is the freezing temperature of water in Celsius, Fahrenheit and Kelvin?

C = 0, F = 32, K = 273

1. How do you convert from Fahrenheit to Kelvin?

F=9/5C + 32 or C=5/9(F-32) Add 273 to C to get to K

1. Define entropy.

The measure of how evenly distributed heat is within a system.

1. Define temperature.

The average kinetic energy of particles in an object

1. A 3cm thick substance covers a 6 cm by 6 cm opening on a heat box. Determine the thermal conductivity for the insulating material if a 25 W bulb is

used to heat the box. The bulb maintains the inside temperature of 20 ̊C higher than the outside temperature.

K=(PL)/(A∆T)=10.42 J/smC

1. If the light inside the heat box in problem 6 is left on for 10 minutes, determine the energy transfer.

Q=P∆t=15,000 J

1. A zoo keeper walks into the penguin exhibit to feed the penguins. The exhibit is kept at -10 ̊C. The zookeeper’s skin temperature is 35 ̊C. Determine the net energy transfer from the zookeeper’s skin during the 10 minutes it took her to feed the penguins. Note: Skin emissivity is .90, and the surface area of the zookeeper is 2 m2.

Pnet=σAe(Tf4-Ti4)= (5.6696x10^-8)(2)(0.90)(308^4-263^4)=430.13 W

Q=P∆t=258,080 J

1. A 4 kg piece of tin at 70 ̊C is placed in 2 liters (2 kg) of water at 25 ̊C. Determine the final temperature (Tf). Note: Tin has a Specific Heat Capacity of 210 at 25 ̊C in J/kg ̊C. Water has a Specific Heat Capacity of 4184 at 25 ̊C in J/kg ̊C.

Qtin=(m)(Cp)( ∆t)=QwaterTf=29.11C

1. Calculate, label and dimension theand components. Indicate the location of the centroid using the appropriate symbol.

7 cm

1.8 cm

12 cm

3.4 cm X = 214.03/69.72 = 3.07 cmY = 423.04/69.72 = 6.07 cm

4.2 cm

42. Find the beam deflection of a board with a load of 500 lb, a Modulus of Elasticity of 600,000 psi, a Moment of Inertia of 5 in4 and a span of 8 ft.

Delta Max = (FL3)/(48EI)=(500lb * (96in)3)/(48*600000psi*5in4)=3.072 in

43. Calculate the Moment of Inertia for the board whose cross section looks like figure A.

Figure A

I=(bh3)/12=(6in * (2in)3)/12 = 4 in4

2 in

6 in

44. Draw a free body diagram illustrating the x and y components of vector A. Solve for the component forces with a precision of 0.0.

Cos 70 = Fax/77Fax = 26.34 lb

77 lb sin 70 = Fay/77Fay = 72.36 lb

70◦

45) Draw a free body diagram of joint A below be sure to include necessary labels, then solve for all unknown quantities:

RAx = _0______

RAy = ___675 lb up______

ADx = __675 lb left______

ADy = ___675 lb down____

AD = ___954.59 lb______

Circle one: compression tension

AB = __675 lb______

Circle one: compression tension