651
ANSWERS
Solutions to Checkpoint Problems
Chapter 1
1.1  e PointTM is a unit.
1.2 (e)
Chapter 2
2.1 Glycerin has a higher viscosity at both temperatures.
Chapter 3
3.1 (d)
Chapter 4
4.1 (a)
Chapter 5
Chapter 6
6.1 (h)
Chapter 7
7.1 (a), (c) and (f)
Chapter 8
8.1 (b)
Chapter 9
9.1 Dimensions. Secondary dimensions ⫽ (force)/(volume).
Primary dimensions ⫽ M/(L2T2).
on the matter inside this CV is zero. at is, the forces
balance like this:
1Resultant force due to Viscosity2
1
Volume of the CV
2
9.2 (d)
10.2 Re ⫽ 79,000, ks/D ⫽ 1.73 ⫻ 10⫺2, f ⫽ 0.047, hf ⫽ 5.75 m
10.3 Equation for V
initial value.
Chapter 11
the football lowers the drag.
11.3 (d)
Chapter 13
13.1 No solution provided.
15.1 (a) 15.2 (b)
Chapter 16
16.1 True, False, False.
To review or download detailed solutions, go to www.wiley.com/college/elger.
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652 ANSWERS
2.36 max at y H; zero stress at
y
H
2ut
Hd
p
/ds;
ut11/22dp
ds H2
2.38 2
3
2
3; V 0.060 m/s; 0.30 N/m2
2.42 a and b
2.44 b
2.52 0.032 N s/m2
2.54 air 1.91 105
N
ⴢs
m2; air 10.1 106 m2/s; water
6.53 105 Ns/m2; water 6.58 107 m2/s
2.56 a, b, d, e, and f
2.58 ¢
p
4
R; p4mm rad. 73.0 N/m2
Chapter 3
3.2 a. 0.175 kg/m3; b. 0.531 kg/m3
3.4 Pabs 399 kPa abs
3.6 % Error 1.01%
Solutions to Selected Even-Numbered
Problems
Chapter 1
1.8 (b), (c), and (d).
1.14 (a) m 0.137 slug
1.22 (a) F 100 N
(b) F 3.11 lbf
(c) F 445 N
1.24 E 1.09 105 kWh, C $10,900
1.26 (a) N 3.30 1022 molecules
Chapter 2
2.4 a, b, c, and d
2.6 l3.30s
l
ug
f
t
3; 106
lbf
f
t
3
2.8 1.53
k
g
l
ug
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ANSWERS 653
3.106 d 2.105L
Chapter 4
4.2 streakline
4.4 c
4.8 c
4.12 a
4.14 Point A: Unsteady, uniform
4.26 axa3 U2
0
r3
0
x4ba1r3
0
x3b
4.28 ac 5  /s2
4.30 al8qo
3Bt
o
4.32 a/3.56 ft/s2; ac 37.9  /s2
4.36 0p
0z75.8 lbf/ft3
3.26 h2 0.553 m
3.46 a. pabs 15.26 psia
b. h 190 mm
c. pgas 10 psfg
d. pgas 0.235 bar
3.48 pA 0.403 psig
3.50 pB 1.00 kPa gage
3.52 pcontainer 27.5 psfg
3.54 liq. 4995 N/m3
3.70 a. z2 m
b. F 78.4 kN
c.
y
c
p
y0.167 m
3.72 Fgate 105 kN (acts to the right)
3.74 F 2662 lbf to le , or F 2662 lbf
3.76 P 300 kN
3.78 T 26,520  -lbf
3.80 gate will fall
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654 ANSWERS
5.24 q 3.09 m2/s; V 2.57 m/s
5.26 V
11
n1
2
Vc
5.28 V 0.226  /s
5.56 t 14.0 s
5.58 VR (2/3)  /s
5.60 V1 12 m/s; V2 36 m/s
5.62 V15 5.66 m/s; V20 6.37 m/s
5.88 e 0.0676 kg/m3
5.90
d
dt 250 k
g
/m3ⴢs
5.92 b
5.94 pB 18.1 lbf/in2
5.96 Q 426 cfm
4.60 V0 0.88 m/s
4.62 b
4.64 V 57.7 m/s
4.86 pA 1.74 psig
4.88
p
h
p
/3.84 kPa
4.90 pA pB 61.6 psf
4.92 No
Chapter 5
5.2 d 50.2 
5.4 a
5.6 b
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ANSWERS 655
6.86 T 124 k N
6.88 ar 0.112  /s2
6.90 Fx 73.97 N (acting to the le )
Chapter 7
7.4 a. E 1.61 107 J; Cost $0.67
b. P 1010 W
c. P 13.6 hp
7.6 b, c, e, and f
7.26 pA 250 psf; V2 34.0  /s
7.28 p2
13.2 m
7.30 pA pB 12.4 kPa
7.32 KL 2.57
7.34 Q 5.03 103 m3/s
7.52 P 14.9 kW
7.54 P 41.2 hp
7.56 P 844 kW
7.58 Power (case a) 4.02 kW; Power (case b)
Chapter 6
6.4 a. in MD; b. in FD; c. in FD if borne by a reaction
force; d. in FD (if signifi cant); e. in FD
6.18 pair 8.25 atm
6.20 T 788 lbf
6.24 Fx 331 lbf (acts to the le ); Fy 85 lbf
(acts downward)
6.26 F (4.36 lbf) i (16.29 lbf) j
6.40 T 5120 lbf; T 3630 lbf
6.42 Ve 2980  /s
6.44 p1 312 kPa; Force on nozzle 2.26 kN to the le
6.46 Fx 40.7 kN (acts to the le )
6.48 Fx 75.4 kN
6.66 Fy 12,200 lbf (acting downward)
6.68 Fx 1210 lbf (acting to the le , opposite of inlet fl ow)
6.70 Fx 1140 N
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656 ANSWERS
8.48 Vp 1.78 m/s; pp 3.19 kPa
8.50 Vtunnel 25 m/s; Ftunnel Fprot. 2400 N
8.52 Qm 0.0455 m3/s; Cp 1.07
8.54 Fp 25 kN
Chapter 9
9.4 V 1.38 m/s
9.6 5.43 102 N ⴢ s/m2
9.8 Pressure fl ow in x-direction and upper plate moves
to le ; min at du/dy 0
9.10 a. u 150y (m/s); b. rotational; c. yes; d. Fs 180 N
9.34
x0.0071
9.36 a
9.38 Fx 5.15 N
9.40 u U0 0.85 m/s
7.74 FdU2D2
8c1
1
D2/d21
2
2d; Fd 0.372 N
7.76 b, c, d
Chapter 8
8.2 3 dimensionless variables (or 3 -groups)
8.4 a. homogeneous; b. not homogeneous;
c. homogeneous; d. homogeneous
8.6 ¢h
df
A
D
d, t2
d, h1
d
B
8.8 FD
Vd
C
8.24 FD
V2B2fa
VB, urms
V, Lx
Bb
8.26 a. aorta 19.9
b. capillary 0.035
c. yes, aorta; yes, capillary
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ANSWERS 657
10.52 a. Case 1; b. Case 3; c. Case 3
10.54 D 0.022 m
10.56 V 3.15 m/s
10.80 Q 0.0129 m3/s; pA 92.0 kPa
10.82 z1 z2 44.5 m
10.84 pA 39.7 psig
10.86 pf 1.77 lbf/ 2
10.88 a. p 0.6 in-H2O; b. P 38.9 W
Chapter 11
11.2 d
11.4 CD 2.0
11.6 a, b and d
9.52 *兰
0
11u
U2 dy
9.54 *
1
8
Chapter 10
10.2 Turbulent; Le 7.5 m
10.6 ptank 1.75 kPa gage
10.26 8.91 105 m2/s
10.28 downward (from right to le ); f 0.076; laminar;
0.00154 lbf ⴢ s/ 2
10.30 p 570 Pa
10.32 f 0.0139
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658 ANSWERS
12.42 pb 87.2 kPa
12.48 A/A* 4.23; Tt 1260R 800F; pt 55.1 psia
Chapter 13
13.4 V 0.06 m/s
13.6 h 35.4 mm
13.22 Cc 0.856
13.26 Q 5.01 cfs
13.28 Q 0.496 cfs
13.30 Percent increase in discharge 96%
13.32 pT,1 pT,2 (p1 z1) (p2 z2)
13.48 Q 0.00124 m3/s
13.50 hL 64V2
0/2g
13.54 a. V
1
L兾¢t
2
[121
1
c¢t兾L
2
2]
b. Vc
2
¢t
11.30 Energy 77.2 kJ 18.4 Food Calories
11.32 Additional power 21.9 hp
11.54 Vo 5.70 m/s
11.56 t 0.54 seconds and d 14.2 cm
11.58 A 6.23 103 mm2
11.60 a
Chapter 12
12.2 a. V 761 mph; b. s 0.84 mi
12.6 c 427 m/s
12.8 cH24160 ft兾s
12.28 No; would violate 2nd law of thermodynamics
12.30 M2 0.475; T2 853 R 393 F; p2 310 psia
12.32 M2 0.454; p2 680 kPa, abs;
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ANSWERS 659
15.6 Q 188.1 m3/s
15.8 QDarcyWeisbach 321 cfs; QManning 284 cfs
15.24 Subcritical
15.26 y2 9.35 m; E 9.36 m
15.28 Supercritical
15.30 yc 1.40 m
15.42 y2 2.71 m; zwater surface 0.29 m; width for max.
contraction 2.46 m
15.44 y2 1.43 
15.46 V 4.01  /s
15.50 hL 2.30  ; P 4.70 hp; Fr 51.2 lbf opposite
Chapter 16
13.64 Depth 1.124 m
13.66 H 16.5 in.
Chapter 14
14.4 FT 926 N; P 35.7 kW
14.6 N 1160 rpm
14.8 D 1.71 m; V0 89.4 m/s
14.28 Q 6.25 cfs
14.30 H30 73.8 m
14.32 Q 0.0833 m3/s; h 146 m; P 104 kW
14.36 Nss 2,760, which is much below 8,500; therefore,
safe.
Chapter 15
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