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

The objectives of this chapter are to introduce the concept of force,its various types,and

other force related variables such as pressure and stress. We will discuss

Newton’s laws in this chapter.Newton’s laws form the foundation of mechanics and

analysis and design of many engineering problems including structures,airplane air-

frames ( fuselage and wings),car frames,medical implants for hips and other joint

replacements,machine parts,and orbit of satellites.We will also explain the tendencies

of unbalanced mechanical forces,which are to translate and rotate objects.Moreover,we

will consider some of the mechanical properties of materials that show how stiff or flexi-

ble a material is when subjected to a force.We will then explain the effect of a force act-

ing at a distance in terms of creating a moment about a point; the effect of a force acting

over a distance,what is formally defined as mechanical work; and the effect of a force act-

ing over a period of time in terms of what is generally referred to as linear impulse.

Table 6.7 is repeated here to show how the content of this chapter is related to

fundamental dimensions discussed in previous chapters.

TABLE 6.7 Fundamental Dimensions and How They Are Used in Defining Variables that Are Used in Engineering Analysis and Design

Fundamental

Dimension Related Engineering Variables

Length (L) Radian , Area (L^2 ) Volume (L^3 ) Area moment

[Chapter 7] Strain of inertia (L^4 )

Time (t) Angular speed ,

[Chapter 8] Angular acceleration Volume flow rate

Linear speed ,

Linear acceleration

Mass (M) Mass flow rate , Density ,

[Chapter 9] Momentum Specific volume

Kinetic energy

Force (F) Moment (LF), Pressure ,

[Chapter 10] Work, energy (FL), Stress , 1

F

L^22

1

F

L^22

1

ML^2

t^22

1

L^3

(^1) M 2
ML
t^2
1
M
L
1 32
M
t^2
1
L
t^22
1
L
t^2
1
L^3
(^1) t 2
1
t^22
1
1
t^2
1
L
L^2
1
L
L^2
Linear impulse (Ft), Modulus of Specific weight ,
Power elasticity ,
Modulus of
rigidity
Temperature (T) Linear thermal expansion Volume thermal
[Chapter 11] expansion
Specific heat
Electric Current (I) Charge (It) Current density
[Chapter 12] 1
I
L
22
1
FL
MT^2
1
L^3
(^1) L (^3) T 2
L
LT^2 ,
1
F
L^22
1
F
(^1) L 22
FL
t^2
1
F
L^32
252
62080_10_ch10_p251-302.qxd 5/22/10 12:32 AM Page 252
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