Mechanics of Fluids 5th Edition By Potter - Test Bank

Mechanics of Fluids, 5th Edition Chapter 1: Basic Considerations

Solutions for Sections 1.1 – 1.3

1. If force was selected as a fundamental dimension rather than mass, the units of density

would be:

(B) N·s2/m4

2 3 2 4 ] ( / )/ / F T L L F T L= ⋅ = ⋅ . Using SI units, this is 2 4 N s /m⋅

[ ] [ ]/[ m V

=

2. Which of the following is not acceptable in the SI system of units?

(A) N·cm/s

cm is only allowed when used as cm, cm2, or cm3

3. The energy usage in the United States in 2010 was about 100 × 1018 J. This can be

written as:

(D) 100 trillion MJ

A trillion is 1012. So, 12 6 18 100 10 10 J 100 10 J × × = ×

4. The fluids that are considered in this text:

(D) Move when subjected to any shear stress

The fluids of interest in Fluid Mechanics always move when subjected to a shearing

stress no matter how small that shearing stress may be.

5. The mean free path where commercial aircraft fly (about 30,000 ft) is nearest:

(C) 0.00076 mm

=

0225

.

m

d

2

−

26

×

48 10 kg

.

−

7

= = ×

0225 172 10 m

. .

3 10 2 2

−

× × ×

(000089 5154) kg/m (37 10 ) m

. . .

The factor 515.4 came from Table A.1 in the Appendix.

1

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