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POE Year-Long Final Review 2009-10 1

POE Final Exam Review

CAREERS IN ENGINEERING

What is the definition of Engineering?

What is the difference between a degree in Engineering Technology and Engineering?

Know the job function of following Engineering disciplines:

Civil -

Electrical -

Mechanical -

Aerospace –

SKETCHING

Know the following drawing terms and be able to identify them:

Orthographic

Isometric

Oblique

Sketching

Hidden line

CAD

DESIGN PROCESS Know the 12 steps of the design process and what happens at each step.

Design Step Actions


What are the following in relation to a design project?

Constraints –

Solutions –

Components-

Design Brief -

Be able to identify the following types of graphs:

Bar Line Pie

SIMPLE MACHINES

Levers

In figure A, the load is 5 feet from the pivot point, the effort is applied 15 feet from the pivot point and the load weights 30 pounds.

In figure A, what is the mechanical advantage?

Using figure A, what is the effort required to lift that 30 pound load?

In figure B, the load is 8 feet from the pivot point, the effort is applied 24 feet from the pivot point and the load weights 50 pounds.

In figure B, what is the mechanical advantage?

Using figure B, what is the effort required to lift that 50 pound load?

Unknown figure:

The load is 12 feet from the pivot point; the effort is applied 2 feet from the pivot point. Draw this figure, solve for

the mechanical advantage and the effort.

figure A

figure B


Define the following and give an example of each. Use the terms fulcrum, effort, and resistance.

1st class lever

2nd class lever

3rd class lever

Incline Planes

In figure A, the ramp is 6 feet tall (vertical distance) and the base (horizontal distance) is 8 feet long.

Using figure A, what is the mechanical advantage of this ramp?

In figure A, what is the effort needed to push the 200 pound weight up the ramp?

In figure B, the ramp is 3 feet tall (vertical distance) and the ramp (slanted distance) is 12 feet long.

Using figure B, what is the mechanical advantage of this ramp?

In figure B, if an effort of 20 pounds is needed to push a load up the ramp. What is the weight of that load?

Wheel & Axle

In figure A, the wheel has a radius of 4 feet and the axle has a radius of 1 foot.

Using figure A, what is the mechanical advantage?

In figure A, what effort/pull is needed to lift a load of 300 pounds?

figure B

figure A

figure A


In figure B, the wheel has a radius of 9 feet and the axle has a radius of 3 feet.

Using figure B, what is the mechanical advantage?

In figure B, if you pull with an effort of 20 pounds, what is the maximum load you can lift?

What is the linear distance traveled when a 2.5’ diameter wheel makes one revolution?

Pulleys

Using figure A, what is the mechanical advantage?

In figure A, if you pull 20 feet, how much do you move the load?

In figure B, what is the mechanical advantage?

In figure B, what distance do you need to pull to lift the load five feet?

figure B

figure A

figure B


Gears

What is the overall gear ratio of figure A?

(Gear A {input} has 12 teeth, B has 8 teeth, and C {output} has 16 teeth)

In figure A, if you turn gear A at 60 rpm, what speed is gear C turning?

The input torque is 30 foot-pounds in figure A. What is the output torque?

What is the overall gear ratio of figure B?

(Gear A {input} has 20 teeth, B has 35 teeth, C has 45 teeth, and D {output} has 80 teeth)

In figure B, what speed do you need to turn gear A for gear D to turn at 90 rpm?

The output torque is 20 foot-pound in figure B. What is the input torque?

Define the following terms in relation to Mechanical Advantage:

Effort:

Work:

Energy:

Force:

figure A

figure B


THERMODYNAMICS

Define the following terms and give an example of each:

Conduction:

Convection:

Radiation:

ELECTRICITY Define the following terms and what unit are they measured in:

Current –

Resistance –

Electromotive Force –

Use your prefix chart to convert the following values:

5,700 V = kV = mV 101 MΩ = Ω = μΩ

446 mΩ = Ω = kΩ 6965.3 mV = V = μV

21.5 A = mA = nA 1550.9 ρA = μA = mA

252 Ω = MΩ = μΩ 85.996 MΩ = Ω = kΩ

4741.2 V = kV = mV 5,700 V = kV = mV

669.25 mA = ρA = mA 2 mA = A = μA


The original voltage in a circuit is 6800 volts. If the voltage increases by 1/3 of its original value, what is the new

voltage value?

A circuit has an applied voltage of 100 volts, and a resistance of 1,000 ohms. What is the current flowing in the circuit?

Using Ohm’s Law, find resistance in kΩ when V = 12 V and I = 25 x 10-6 A.

The voltage across a resistor increases from 4.9 volts to 5.6 volts when the current is increased. What is the

percent of increase in the voltage?

What is being measured in the following pictures?

Find the total resistance and voltage (VR1, VR2 and VR3) for the circuit below.

Using the data from the previous problem, verify your results using Kirchhoff’s Voltage Law.


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

Using the data from the previous problem, verify your results using Kirchhoff’s Current Law.

Find the total resistance and for the following circuit (you may need help for this one = “squish them”):

Define the components of a circuit and give an example of each. Load –

Source –

Switch –

Conductor –

CONTROL SYSTEMS

What is the difference between an open and a closed loop system?

What is the difference between an analog and digital device? Give an example of each from the FischerTech sets.

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What are the differences between and input and an output device. Name several we used from the FischerTech

sets.

RoboPro Application

What is the name of the variable?

What is the initial value of the variable?

How many times will this repeat?

Which way will the motor turn initially?

What type of sensor causes it to change directions?

Where would you connect this sensor to the interface?

What type of sensor causes it to change directions the second time?

Where would you connect this to the interface?

STATICS Bridges

What is a truss?

What are the two components of vectors?

What is an abutment?

What are the two purposes of abutments?

figure A

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Label the names of the different types of members on the drawing above.

Top chord Bottom Chord Vertical Diagonal Floor Beam

Name 5 loads actual bridges have to incur.

The picture above shows the rubber band to be in ________________________________.

___________________________force makes a member longer.

A break of a member in the above mentioned force would result in ( buckle / snap )

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The object above is said to be in __________________________.

__________________________ force makes a member shorter.

A break of a member in the above mentioned force would result in ( buckle / snap )

Free Body Diagrams

Draw free body diagram for items A, B, C, D.

Draw free body diagram for member AB and cylinder D.

12

Triangle and Trig Practice

Two joggers run 8 miles north and then 5 miles west. What is the shortest distance, to the nearest tenth of a mile, they must travel to return to their starting point?

In a computer catalog, a computer monitor is listed as being 19 inches. This distance is the diagonal distance

across the screen. If the screen measures 10 inches in height, what is the actual width of the screen to the

nearest inch?

Oscar's dog house is shaped like a tent. The slanted sides are both 5 feet long and the bottom of the house is 6

feet across. What is the height of his dog house, in feet, at its tallest point?

In a park, a slide 9 meters long is built over a horizontal distance of 6 meters along the ground. Find to the nearest

degree the measure of the angle that the slide makes with the horizontal.

Trusses

Solve for the reaction forces at A and B:

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Member AB = 3 in Member AC = 3 in Angle C = 45 DEGREES

What is the length of member BC? Is it in tension or compression?

Are AB and AC in tension or compression?

What forces are acting on A? What forces are acting on B? What forces are acting on C?

Calculate the angle at B and calculate the distances of members AC and BC.

Calculate the reaction forces in the X and Y-directions at A and B

Calculate the internal force in member AC. Is it in tension or compression?

B

A C

A

C

B

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Calculate the angle at C

Calculate the distances of member AC.

Calculate the reaction forces in the X and Y-directions

at B and C

Calculate the internal force in member AC. Is it in tension or compression?

Solve for all of the forces acting on these trusses:

•

•

3 ft

ft

4 ft

•

• •

A

C

B

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And now…..a challenge:

MATERIALS Categories of Materials – write a basic definition, any subcategories and examples for each:

Organics

Metals and Alloys

Polymers

Ceramics

Composites

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Strength of Materials

Using the fact that the structural steel in question has a cross sectional area of 29.7 in2, find the tensile stress if the

member under test is a structural steel W27x94 and the load is 95,600 psi.

A piece of steel wire 100 feet long, with a cross-sectional area of 0.004 sq. in., must be stretched with a pull of 16

pounds when in use. If the Modulus of Elasticity of steel is 30,000,000 psi, what is the total elongation in the

entire length of the wire?

Calculate the required diameter of an aluminum rod subjected to an axial tensile load of 45,500 N, if the allowable

tensile stress is 125 x 10^6 N/M^2.

A floor plank supports the round hanger rod as shown. If the load on the rod is 15,500 lb, (a) find the tensile stress in the rod and (b) the bearing stress between the round washer and the floor plank.

Design a 12 foot rod which will be subjected to a tensile load of 27,500 lb. Using a factor of safety of 1.5 based on

the yield stress, calculate the required rod diameter if it is to be made of steel with a yield stress of 50,000 psi.

Compute the force required to punch a 1.25-inch diameter hole through a ½ inch boilerplate. The ultimate shear stress for the material is 42000 psi.

Three pieces of wood are glued together to form an assembly, as shown. A load of 21000 lb is applied. Find the

average shear in each joint.

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What is the compressive stress in a pressure treated wooden post 250 mm by 250 mm, if it supports a compressive

load of 425 kN?

Using the fact that the structural steel in question has a cross sectional area of 27.7 in2, find the tensile stress if the member under test is a structural steel W27x94 and the load is 95.6 kips.

Calculate the required diameter of an aluminum rod subjected to an axial tensile load of 45.5 kN, if the allowable

tensile stress is 135 MPa.

A rod supports an axial force of 45 kN. If the compressive stress in the bar is not to exceed 80 MPa, determine the

diameter of the rod.

Note: For the following problems, assume the modulus of elasticity for steel to be 30,000,000 psi (207 000 MPa)

and the proportional limit to be 34,000 psi (234 MPa).

A steel tube having an O.D of 7/8 inch and I.D of ½ inch is subjected to an axial load of 4500 lb. It has a

length of 24 inches. Compute the tensile stress in the tube and the total axial deformation.

A 125 foot surveyor’s steel tape with a cross-sectional area of 0.005 in2 is subjected to 10 lb pull when in use.

Find the total elongation of the tape and the tensile stress developed in the tape.

A 1 inch steel rod, 75 feet long is hanging vertically. Find the total elongation due to the rod’s own weight and

a suspended 7500 lb load applied at its free end. (The weight of steel is 490 pcf.)

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Materials Testing

Calculate the stress at the proportional limit. Be sure to show all your work. Label Fpl on the chart above.

Calculate the stress at the yield point. Be sure to show all your work. Label Fyp on the chart above.

Calculate the stress at the Ultimate. Be sure to show all your work. Label Fult on the chart above.

Calculate the stress at the Breaking Point. Be sure to show all your work. Label Fbp on the chart above.

Calculate the Modulus of Elasticity, the Modulus of Resilience and the Modulus of Toughness. Show your work and

label them on the graph.

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STATISTICS

Find the mean, median, mode and standard deviation of the following ranges of values. Plot the points on a

histogram and figure out if your data is a normal set.

Tests scores from 2007: 61, 73, 51, 57, 64, 23, 52, 66, 87, 32, 92, 100, 18, 77, 72, 73, 89, 92, 22

Number of goals scored last season: 16, 34, 11, 43, 31, 0, 24, 32, 37, 16, 0, 31, 47, 24, 17, 27, 39, 3, 26

BALLISTICS

Solve for the initial velocity and range in these examples:

A water grenade is launched with a speed of 10 m/s at an angle of 50 degrees to the horizontal. Solve for the

range.

A football is thrown by Peyton Manning at an angle of 28°. The ball travels 55 yards. What is the initial velocity of the ball? (don’t forget to convert from yards to feet )

A base jumper jumps from a cliff with a velocity of 10 m/s at an angle of 20 degrees to the horizontal. Solve for the range.

Use trigonometric functions to resolve the following velocity vectors into horizontal and vertical components. Then

utilize kinematic equations to calculate the other motion parameters. Be careful with the equations; be guided by

the principle that "perpendicular components of motion are independent of each other."

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Utilize kinematic equations and projectile motion concepts to fill in the blanks in the following tables.

An object is launched at 19.6 meters per second (m/s) from a 58.8-meter tall platform. The equation for the

object's height s at time t seconds after launch is s(t) = –4.9t2 + 19.6t + 58.8, where s is in meters. When

does the object strike the ground?

An object in launched directly upward at 64 feet per second (ft/s) from a platform 80 feet high. What will be

the object's maximum height? When will it attain this height?

An object is launched from ground level directly upward at 39.2 m/s. For how long is the object at or above a

height of 34.3 meters?

The International Space Agency has finally landed a robotic explorer on an extra-solar planet. Some probes are

extended from the lander's body to conduct various tests. To demonstrate the crushing weight of gravity on this planet, the lander's camera is aimed at a probe's ground-level ejection port, and the port launches a

baseball directly upwards at 147 feet per second (ft/s), about the top speed of a professional pitcher. The force due to gravity on this planet is 98 ft/s2. Assuming no winds and that the probe can scurry out of the way in

time, how long will it take for the ball to smack back into the surface?

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