174 Chapter 7 Length and Length-Related Parameters
You can see from Equation (7.3) that for the same force (push) on the knife, you can increase
the cutting pressure by decreasing the cross-sectional area. As you can also tell from Equation
(7.3), we can also reduce the pressure by increasing the area. In skiing, we use the area to our
advantage and distribute our weight over a bigger surface so we won’t sink into the snow. Next
time you go skiing think about this relationship. Equation (7.3) also makes clear why high-
heeled shoes are designed poorly as compared to walking shoes. The purpose of these examples
is to make you realize that area is an important parameter in engineering design. During your
engineering education, you will learn many new concepts and laws that are either directly
or inversely proportional to the area. So keep a close watch out for area as you study various
engineering topics.■Figure 7.9
Area plays an important role in
the design of cutting tools.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