and a casing. From these examples it should be clear that in order to understand a system, we
must first fully understand the role and function of its components.
During the next four or five years you will take a number of engineering classes that will
focus on specific topics. You may take a statics class, which deals with the equilibrium of objects
at rest. You will learn about the role of external forces, internal forces, and reaction forces and
their interactions. Later, you will learn the underlying concepts and equilibrium conditions for
designing parts. You will also learn about other physical laws, principles, mathematics, and cor-
relations that will allow you to analyze, design, develop, and test various components that make
up a system. It is imperative that during the next four or five years you fully understand these
laws and principles so that you can design components that fit well together and work in har-
mony to fulfill the ultimate goal of a given system. Thus, you can see the importance of learn-
ing the fundamentals. If you don’t, you are likely to design poor components that, when put
together, will result in an even poorer system!6 6..8 8 PPhhyyssiiccaall LLaawwss aanndd OObbsseerrvvaattiioonnss iinn EEnnggiinneeeerriinngg
As stated earlier, engineers apply physical and chemical laws and principles along with mathe-
matics to design, develop, test, and mass-produce products and services that we use in our
everyday lives. The key concepts that you need to keep in the back of your mind are the phys-
ical and chemical laws and principles and mathematics.
Having had a high school education, you have a pretty good idea of what we mean by math-
ematics. But what do we mean by physical laws? Well, the universe, including the earth that we
live on, was created a certain way. There are differing opinions as to the origin of the universe.
Was it put together by God, or did it start with a big bang? We won’t get into that discussion
here. But we have learned through observation and by the collective effort of those before us
that things work a certain way in nature. For example, if you let go of something that you are
holding in your hand, it will fall to the ground. That is an observation that we all agree upon.148 Chapter 6 Fundamental Dimensions and Units
Cooling system
Engine
Wiper motor
systemDrive train
Brake system
■Figure 6.6 Exhaust system
An engineering system and its
main components.Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).圀圀圀⸀夀䄀娀䐀䄀一倀刀䔀匀匀⸀䌀伀䴀圀圀圀⸀夀䄀娀䐀䄀一倀刀䔀匀匀⸀䌀伀䴀