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

224 Chapter 8 Time and Time-Related Parameters

8.1. Create a calendar showing the beginning and the end

of daylight saving time for the years 2009 – 2016.

observation of daylight saving time in the month of

April in the years of 1974 and 1975 saved the country

an estimated energy equivalent of 10,000 barrels of oil

each day. Estimate how much energy is saved in the

United States or your country due to observing day-

light saving time in the current year.

8.3. Is there a need for a country near the equator to

observe daylight saving time? Explain.

8.4. Besides energy savings, what are other advantages that

observation of daylight saving time may bring?

8.5. Every year all around the world we celebrate certain cul-

tural events dealing with our past. For example, in

Christianity, Easter is celebrated in the spring and

Christmas is celebrated in December; in the Jewish

calendar, Yom Kippur is celebrated in October; and

Ramadan, the time of fasting, is celebrated by Muslims

according to a lunar calendar. Briefly discuss the basis of

the Christian, Jewish, Muslim, and Chinese calendars.

Daylight Saving Time Daylight Saving Ends

Year Begins at 2:00 a.m. at 2:00 a.m.

2012

2013

2014

2015

2016

2017

2018

Then we use Equation (8.17) to calculate the angular acceleration.

Finally, remember that all the parameters discussed in this chapter involved time, or length

and time.

Summary

Now that you have reached this point in the text

• You should have a good grasp of yet another fundamental dimension in engineering, namely
  time, and its role in engineering analysis. You should also recognize the role of time in cal-
  culating speed, acceleration, and flow of traffic, as well as flow of materials and substances.


• You should know what we mean by frequency and a period, and be able to give some
  examples of mechanical and electrical systems with frequency and periods.


• You should know how to define average and instantaneous velocity. You should also be able
  to define average acceleration and instantaneous acceleration.


• You should have a comfortable grasp of a rotational motion and how it differs from a trans-
  lation motion. You should know how to define angular velocity and acceleration.


• You should understand the significance of volume flow rate in our everyday lives and in
  engineering applications. You should also have a good grasp of what is meant by volume
  flow rate.

Problems

angular acceleration

changes in angular speed

time



1 167.5 02 rad/s

5 s

33.5

rad

s

2

8.2. According to the Department of Transportation anal-

ysis of energy consumption figures for 1974 and 1975,

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