Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

Problems 225

8.6. In this problem you are asked to investigate how much

water a leaky faucet wastes in one week, one month, and

one year. Perform an experiment by placing a container

under a leaky faucet and actually measure the amount of

water accumulated in an hour (you can simulate a leaky

faucet by just partially closing the faucet). You are to

design the experiment. Think about the parameters that

you need to measure. Express and project your findings

in gallons /day, gallons /week, gallons /month, and gal-

lons /year. At this rate, how much water is wasted by

10,000,000 households with leaky faucets. Write a brief

report to discuss your findings.

8.7. Next time you are putting gasoline in your car, deter-

mine the volumetric flow rate of the gasoline at the

pumping station. Record the time that it takes to pump

a known volume of gasoline into your car’s gas tank.

The flow meter at the pump will give you the volume

in gallons, so all you have to do is to measure the time.

Investigate the size of the storage tanks in your neigh-

borhood gas station. Estimate how often the storage

tank needs to be refilled. State your assumptions.

8.8. You are to investigate the water consumption in your

house, apartment, or dormitory —whichever is appli-

cable. For example, to determine bathroom water con-

sumption, time how long it normally takes you to

shower. Then place a bucket under the showerhead for

a known period of time. Determine the total volume of

water used when you take a typical shower. Estimate

how much water you use during the course of a year

just by showering. Identify other activities where you

use water and estimate your amount of use.

8.9. Using the concepts discussed in this chapter, measure

the volumetric flow rate of water out of a drinking

fountain.

8.10. Convert the following speed limits from miles per hour

( mph) to kilometers per hour (km/h) and from feet

per second (ft /s) to meters per second ( m/s). Think

about the relative magnitude of values as you go from

mph to ft /s and as you go from km/h to m/s. You may

use Microsoft Excel to solve this problem.

8.11. Most car owners drive their cars an average of 12,000

miles a year. Assuming a 20 miles /gallon gas con-

sumption rate, determine the amount of fuel con-

sumed by 150 million car owners on the following time

basis:

a. average daily basis

b. average weekly basis

c. average monthly basis

d. average yearly basis

e. over a period of ten years

Express your results in gallons and liters.

8.12. Calculate the speed of sound for the U.S. standard

atmosphere using, , wherecrepresents the

speed of sound in m/s,kis the specific heat ratio for air

(k1.4), andRis the gas constant for the air (R

286.9 J/ kgK) andTrepresents the temperature of

the air in Kelvin. The speed of sound in atmosphere is

the speed at which sound propagates through the air.

You may use Excel to solve this problem.

c 1 kRT

Altitude Air Temperature Speed of Speed of

( m) (K) Sound ( m/s) Sound (km/h)

500 284.9

1000 281.7

2000 275.2

5000 255.7

10,000 223.3

15,000 216.7

20,000 216.7

40,000 250.4

50,000 270.7

Speed Limit Speed Limit Speed Limit Speed Limit

( mph) (km/h) (ft /s) ( m/s)

15

25

30

35

40

45

55

65

70

8.13. Express Equation (8.5), the traffic density, in terms of

number of vehicles per mile.

8.14. Express the angular speed of the earth in rad /s and

rpm.

8.15. What is the magnitude of the speed of a person at the

equator due to rotational speed of the earth.

8.16. Calculate the average speed of the gasoline exiting a

nozzle at a gas station. Next time you go to a gas

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