Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL.pdf
PROBLEM 2.1
Situation: An engineer needs density for an experiment with a glider.
Local temperature = 74.3 ◦ F = 296.7 K.
Local pressure = 27.3 in.-Hg = 92.45 kPa.
Find: (a) Calculate density using local conditions.
(b) Compare calculated density with the value from Table A.2, and make a recom-
mendation.
J
Properties: From Table A.2, Rair = 287 kg· K
, ρ = 1.22 kg/ m3 .
APPROACH
Apply the ideal gas law for local conditions.
ANALYSIS
a.) Ideal gas law
p
ρ =
RT
92, 450 N/ m2
=
(287 kg/ m3 ) (296.7 K)
= 1.086 kg/m3
ρ = 1.09 kg/m3 (local conditions)
b.) Table value. From Table A.2
ρ = 1.22 kg/m3 (table value)
COMMENTS
1. The density difference (local conditions versus table value) is about 12%. Most
of this difference is due to the effect of elevation on atmospheric pressure.
2. Answer ⇒ Recommendation—use the local value of density because the effects
of elevation are significant.
1
Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL
,Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL.pdf
PROBLEM 2.2
Situation: Carbon dioxide is at 300 kPa and 60o C.
Find: Density and specific weight of CO2 .
Properties: From Table A.2, RCO2 = 189 J/kg·K.
APPROACH
First, apply the ideal gas law to find density. Then, calculate specific weight using
γ = ρg.
ANALYSIS
Ideal gas law
P
ρCO2 =
RT
300, 000
=
189(60 + 273)
= 4.767 kg/m3
Specific weight
γ = ρg
Thus
γ CO2 = ρCO2 × g
= 4.767 × 9.81
= 46.764 N/m3
2
Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL
,Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL.pdf
PROBLEM 2.3
Situation: Methane is at 500 kPa and 60o C.
Find: Density and specific weight.
J
Properties: From Table A.2, RMethane = 518 kg· K
.
APPROACH
First, apply the ideal gas law to find density. Then, calculate specific weight using
γ = ρg.
ANALYSIS
Ideal gas law
P
ρHe =
RT
500, 000
=
518(60 + 273)
= 2.89 kg/m3
Specific weight
γ = ρg
Thus
γ He = ρHe × g
= 2.89 × 9.81
= 28.4 N/m3
3
Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL
, Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL.pdf
PROBLEM 2.4
Situation: Natural gas (10 ◦ C) is stored in a spherical tank. Atmospheric pressure is
100 kPa.
Initial tank pressure is 100 kPa-gage. Final tank pressure is 200 kPa-gage.
Temperature is constant at 10 ◦ C.
Find: Ratio of final mass to initial mass in the tank.
APPROACH
Use the ideal gas law to develop a formula for the ratio of final mass to initial mass.
ANALYSIS
Mass
M = ρV (1)
Ideal gas law
p
ρ= (2)
RT
Combine Eqs. (1) and (2)
M = ρV−
−
= (p/RT )V
Volume and gas temperature are constant so
M2 p2
=
M1 p1
and
M2 300 kPa
=
M1 200 kPa
= 1.5
4
Engineering fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS
Engineering
MANUAL.pdf
fluid mechanics 9th edition SOLUTIONS MANUAL