Sunday, July 26, 2009

Engineering Trivia

Engineers seem to like trivia...I do. Below is a collection of interesting facts found on some cool engineering pages.

From Meurer & Associates, Inc.:
Americans did not commonly use forks until after the Civil War.

Approximately 10.5 gallons of water is used in a dishwasher. Washing the dishes by hand can use up to 20 gallons of water.

93% of all greeting cards are purchased by women.

On average, the life span of an American dollar bill is eighteen months.

Approximately 60% of the water used by households during the summer is used for watering flowers and lawns.

Early Romans used to use porcupine quills as toothpicks.

Ancient Egyptian women used to wear perfume cones made of wax that would melt in the heat letting out a nice fragrance.

Teflon is the most slippery substance in the world.

The typical lead pencil can draw a line that is thirty five miles long.

Approximately 18 billion disposable diapers end up in landfills each year. These diapers can take as long as 500 years to finally decompose.

An average home creates more pollution than does the average car.

Bamboo plants can grow up to 36 inches in a day.


1. The primary purpose of steel bars in reinforced concrete buildings is:
A) To strengthen the concrete wherever there is a tension or pulling force.
B) To hold up the formwork until the concrete has hardened.
C) To strengthen the concrete evenly because it has very little of its own strength.
D) B and C

A) Concrete is weak in tension since it is artificial rock. Steel bars are more expensive, but are good at carrying tension. However, is very good at carrying compressive forces just like natural rock. Steel can be used to hold up formwork, but this is very rare and it wouldn’t be the bars, but large steel I-beams that would do this. The secondary use of steel bars is the prevent cracks or limit there size. Cracks can be caused by shrinkage during the hardening or curing of concrete.

2. Concrete needs to be kept wet during its hardening process because:
A) It is not possible to add enough water to a concrete mix so more needs to be added.
B) If the water evaporated from the concrete mix it would be too dry to harden.
C) No water is needed. This is a misconception.

B) The water that is added to the mix goes through a chemical reaction with the cement powder. (Hydration) If the water evaporates then the top surface will never fully hydrate, but simply dry to become like clumps of cement powder again.

3. Trenches in earth that are more than 4 feet deep must have:
A) Lateral support of the side of the trenches to prevent cave-ins.
B) Ladders or ramps every 25 feet for quick exiting.
C) All of the above.
D) None of the above.
E) A and B, but only for loose soils.

E) All of the above. It is important for construction managers to keep an eye on the safety of their workers. Earth cave-ins deeper than 4 feet are more likely suffocate a trapped worker. Even if the soil does not look loose or likely to cave in, it still may do so.

4. A delay in completing a $10 million commercial project will have costs to the owner. Which is most likely the biggest?
A) Lost rent
B) Cost of laborers sitting around
C) Extra equipment rental costs

A) On a $10 million project the interest on the construction loan is around $2500 a day. That would be covered by rent if the project would have been opened on time. Laborers can be sent to other projects or given an unpaid vacation day. Equipment rental can be expensive, but likely less than interest.

5. A block of lumber has the most strength (equal sided cube):
A) When it is placed flat so the grain of the tree points along the ground.
B) When it is placed up so the grain of the tree points up and down.
C) Neither. The wood has the same strength either way.

B) The tree puts most of its strength into holding up itself. It does not need as much strength for things pushing against its sides. Lumber has more strength in the direction of the grain.

6. Design-build refers to:
A) building a drafted design
B) designing a building and then constructing it
C) overlapping the design and building process to better manage time

Ans. C Design-Build is when one contractor does the entire job of designing and building the project. In this case engineers work for the contractor.

7. Long piles are placed in the ground under structures to:
A) Carry the structural load to rock or strong soil
B) Use friction to put the load in the soil on each side of it
C) Reduce how much the structure will sink into the ground
D) All of the above
E) None of the above

D) Piles are used for all of these purposes

8. The purpose of compacting or compressing the soil is to:
A) Increasing the strength of the soil to carry structural loads
B) Reduce how much the structure will sink into the ground
C) Decrease leaking of water through the soil
D) All of the above

D) All of the above

9. Retaining walls are most often used to:
A) provide foundation for buildings
B) hold back the earth from a building or other structure
C) divide businesses from residential areas

Ans. B and maybe A. A retaining wall holds soil, such as a basement wall. Although, it is possible to make it integral with the foundation for structures like a home.

10. After paving a new parking lot over bare ground the rainwater that will run off the area will:
A) Increase
B) Remain the same
C) Decrease

A) No water will soak into a paved surface versus some of it would have soaked in before. Even if there are small puddles on the parking lot the runoff will increase. Usually this extra water is caught in an artificial pond. It is possible to make a porous paved surface that the water can soak through, but it is more expensive to do.

11. Which soaks into the ground more? A one inch rain spread over:
A) 6 minutes
B) 6 hours
C) 6 days

B) 6 hours. That much rain falling in 6 minutes would all wash away before the ground could absorb it. On average, soil can absorb a quarter inch of rain plus another tenth of an inch each hour. Rain over six days would be such a fine mist that it might all evaporate.

12. When water flows through a full pipe, the water is fastest in what part of the pipe?
A) All parts flow at the same speed.
B) Top.
C) Middle.
D) Bottom.

C) Middle. The edge of a pipe has friction. The friction slows down the water in contact with it. Therefore, the middle is the fastest.

13. Wetlands may be developed into residential, commercial or industrial property if:
A) The State authority approves it. i.e. DNR
B) The wetland is replaced with more wetland elsewhere than what was removed.
C) The wetland is too small to be regulated.
D) All of the above.
E) None of the above.

D) All of the above. If it is a small ditch then the State probably does not regulate it. The State may approve relocating wetlands if an extra 50 percent of area is added. However, artificial wetlands are very expensive to create.

14. Sewerage is cleaned up primarily through:
A) Microorganism eating the waste
B) Treating with chemicals
C) Fine screen filters collecting all of the waste
D) UV radiation

A) Waste in sewerage is cleaned with all of these. Although very coarse screening is done, not fine. Chemicals are often added or UV radiation performed as a last step to sanitize the waste. However, microorganisms consume most of the waste remaining in the water after coarse screening.

15. Water that has been adversely affected in quality by anthropogenic influence is called:
A) wastewater
B) groundwater
C) rainwater

Ans. A Anthropogenic means human impact.

16. Which type of traffic intersection can be used on at-grade streets?
A) Clover Leaf
B) Single Point User Interchange (SPUI)
C) Roundabout
D) Diamond
E) Crossover

C) A Roundabout is the only one of those listed for flat local streets.

17. Mass Transit such as trains and light rail transit can be designed to be faster when:
A) There are limited stops
B) The transit vehicle is grade separated from autos. (above or below.)
C) The transit vehicle has its own lane.
D) Tickets are not checked at the door, but before entering waiting area or after on the vehicle.
E) All of the above.

E) All of these work to speed up mass transit. Fewer stops and less time at a stop increases average speed. Being separated from traffic increase cruising speed.

18. What city was home to the world’s first 4-way three color traffic light?
A) London
B) Detroit
C) Boston

Ans. B, Detroit

19. In a residential site development what is a land balance?
A) Balance of earth so none needs to be trucked in or out.
B) Balance of the residential land with parks and commercial land.
C) Balance of developing the land versus leaving it as is.
D) Weight of the soil compared before and after compaction.

A) A major expense of land development is moving the earth around. If it has to be moved out of the area or brought in then it adds a major cost. B and C are both good ideas but are controlled through city zoning.

20. The minimum ground slope of 1 to 100 needs to be around all sides of a home because:
A) It makes the house more attractive to have it elevated.
B) It helps lawn mowing to have a gentle slope.
C) It keeps rain water moving away from the home.
D) Grass can not grow on flat ground.

C) Most cities require a minimum slope of around 1 percent. This causes the rain to drain away from the home. It also keeps it from puddling. There is also a maximum slope of 25 percent or 1 foot per 4 feet because it is hard to mow grass beyond that.

21. A Global Positioning System (GPS) unit measures your location on the earth by:
A) Counting your footsteps from a known location like a pedometer.
B) Looking at the angle of the sun.
C) Calculating location from satellite signals.
D) Calculating location from land-based radio tower signals.
E) C and D.
F) A and B.

E) All GPS units use satellite signals to correlate a location on the earth. Many quality GPS units get greater accuracy by also using a Wide Angle Augmentation System (WAAS) which is land-based.

22. If you bought a new refrigerator, unpacked it, plugged it in, but left the refrigerator door open, would the room:
A) Cool down
B) Remain the same temperature
C) Heat up
D) Become a electricity generator

C) Heat up. A refrigerator is a heat pump. It moves heat out of the refrigerator to the room. Therefore it would seem the room would not change temperature. However, electrical energy goes into the room to power the refrigerator. This energy produces extra heat in the pump which gets into the room. Therefore the temperature would go up.

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