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ENMANCERS ( Fluid Mechanics 02
FLUID MECHANICS 02
v-5000
gal/mint
1mins14,183fps
/4(1n)7.481ga60
PSE MODULE 13.2 (SOLUTION)
1. Water having kinematic viscosity uk =1.3 X i0 m/s lows in a 100mm
diameter pipe at a velocity 4.5 m/s Compute the Reynolds number.
C. 432,453.54
A. 346.153.85
D. 434,324.85
B. 324,435.14
VD (4.5m/s)(100 mm)(Im/1000 mm)346153.85
5.40 m)=37.2 bt/n2
Ans D
1.3x10 m/s
6. A cast iron pipe of equilateral triangular cross section with side length of
Ans.A
20 75 has water flowing through it. The flow rate is 6000 gallons per
minute, and the friction factor for the pipe is f = 0.017. What is the
2. What is the hydraulic radius of the semi-circular channel shown?
A. 2ft
C. 4 ft
pressure drop in a 100 foot section?
D.6.14 f
B. 2.57 ft
Soluken :
-2
Aflow
h
n)2
P
wetted
A. 24.31bf /2
C. 178.51bf/f2
B. 48.71bf /A
D. 5364Ibf/ft2
Solutien
2
o
Ans. A
3. Calculate the Reynolds
channel. The water is
number, Re, for water at 20°C owing in an open
flowing at a volumetric rate of 200 ga/sec. The
channel has a height of 4 foct and a width of 8 feet. Al this iemperature
water has a kinematic viscosity of 1.104 x 10 f
A. 605398.41
Selukon
D
V
3/4 (20.75in)(1f/12in60s
0.017(100 a)(10.32/s
DA
=
10.32 ft/s
2322/(D)
D
D. 817487.6
where:
(6000gal/min)1 f/7.481 gal/1 min
/ sec.
C. 158469.8
B. 781975.45
Re=
ft
232.2/ )an
D
Sotehon:
R
(0.0173)(100 f)(14.183 f/s)* 5.40
200
9200
481gal a83s/s
(4f)(8)
3(20.75 in)
= 11.98 in
o.017(100 ft)00.32 n/s) (12 in 2.82 f
232.2n/1.98 in)I
thus
Solving for D
PD vh 6241bf/ (2.82 ft)
=
17587
1bt/2
Ans, C
Re
7. A cylinder 10feet long and 2 feet in diameter is suspended in air flowing
at 8 fUsec. The density ofair is 0.00234 shug/ft, and the coefficient of
drug ofthe sphere is 1.3. What is the drag on the cylinder?
(0.835h/s(8) 605398.41
1.104x10 / s
A. 0.311 1bf
Ans4
B. 0.39 1bf
4. The Reynolds number of a sphere falling in air is
x10 fthe sphere s
C. 1.95 Tbf
D. 3.89 Tbf
Selution :
radius is 1 ft, what is its velocity ? (Par=0.00234 slug/t Hais3.8x 10
Ibf-sec /1ft)
A 2.5ft/ sec
C. 40.6 ft / sec
B. 5.1ft/sec
D.81.2 ft/ sec
EBLboAy-uoo02u0nen)easy
Solution :
b194688 tbf
Ans.C
where H D
R
8. What is the friction factor for fully developed flow in a circular pipe where
HK
Subst.values:
Reynolds nunaber is i1000?
A. 0.008
B. 0.064
Ix 1 0 -
C. 0.08
D.0.10
Salutien
3.8 x10 1bf-sec/
4
0.00234 slug/f1
64
Re10o0.064
V = 81.2f/s
Ans. B
Ans.D
The velocity of water in the stream is 1.2 m/s. What is the height of the
5. The flow rate of water through a cast iron pipe is 5000 gallons per
minute
The diameter of the pipe is 1 foot, and the coefficient of friction is f
0.0173. What is the pressure drop over a 100 foot length of pipe?
A. 21.0781bf /n
B.
23.781bf /in
C. 337.26 Ibf /in
D. 337.26 Ibf /
water in the pitot tube ?
A. 3.7 cm
B. 4.6 cm
Solutien:
h=
Soluion
(1.2m/s)100cm
2(9.81ys)*\ Im
h 7.34 cm
Ans. C
C. 7.3 cnm
D. 9.2 cm
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10.Water (p =62.4 Ibm/ft) is owing through a pipe. A pitot-static gage
registers 3.0 inches of mercury. What is the velocity of the water in the
Eg-PEma-w
Pipe? Note: density of mercury is 848.6 Ibm/ft".
C. 8.2 f/s
A. 14.8 ft/s
D. 7.5 ftus
B. 114 fus
ov)
w
Solving forh: i.Z
Solulom
Y0.5tt
where:
2gh
V
h,= h
14.8t/s
52.4 bvi.265
11. What is the equivalent head ofa fluid that has a velocity of 18 m/s?
Y=103.86
bf
Ans.A
v
18m/S
2g
2(9.8Im/s)
16.514 m
15. Which of the following statements is correct for oils of high viscosity
index?
A. Oil will immediately reacts in small temperature change
B. It continuously increase its viscosity even if there is no change in
Ans.A
length of pipe is 168 meters. If the pressure drop is 50 kPa for every
The
30 m. what is the total pressure drop?
A.
B.
0
Sbf-s
C. 13.56 m
D. I141 cm
16.51 m
18.34 cm
Seleion:
12.
h=y, 0.5ft
where.o2gy 2(32.2)X2/3)(2)_- rmds
ptry
Ans.A
hy
0s0).(2/20)
2ft
Thus:
(848.6
v 2(32.20/s )5im624A12in)
A.
B.
where: m= pV,
240 kPa
280 kPa
temperature
FOSC. slight
It has change
fixed viscosity
in its viscosity with extreme temperature change
C. 260 kPa
D. 220 kPa
Soletion
Solulion
Correct for high viscosity index oils
PT5030 kPa 280kPa
slight change in vis. w/ extreme
Ans.D
Ans.B
sootmesakueiu
13. A circular bucket is 2 ft decp and 2 ft in diameter and open at the top.
When not rotating. The bucket is 1/3 full of water. The bucket is rotated
about an axis through the center of the bucket. What is the minimum
rotational specd at which the bucket can be rotated withoul spilling any
water out of the bucket?
A.9.26 rad/s
C. 145 rad/s
B. 2.27 rad/s
D. 10.4 rad/s
16. One could expect the possibility of Reynolds number similarity in all of
the following cases except
C. fans
A. Pumps
D. weirs
B. Turbines
luion
Similarity on Re cxceptweirs
Selihon
Ans.D
2/3h
KER=PE
2 ft
where KERlo and PE= mgy
namg
.Pao
1/3hE B
2 ft
17. The surface tension of water is 0.07 N/m. Find the weight of water
supported by surface tension in a capillary tube with radius of 0.10 mm
C. 35 uN
A.44 uN
D. 57 N
B.54 uN
Solution
9.27 rad/s
mr
0.07 N/m=(1000mm/m)
Ans.A
2(0. 10mm)
F 44.0 uN
14. A circular bucket is 2 ft deep and 2 ft in diameter and open at the top.
When not rotating. The bucket is 1/3 full of water. The bucket is rotated
about an axis through the center of the bucket. What is the equivalent
specific weight al a point 0.5t from the center of the bucket?
C. 107.45 lbf/ft
A. 103.89 lbi/fts
D. 125.45 1bf/ft3
B. 103.45 bf/ft3
Solulion:
Ans..
18. Water at 20 °C is flowing in a pipe of radius 1.0 cm. The viscosity of
water at 20°C is 1.005 centipoise. If the flow speed at the center is 0.200
ms and the fow is laminar, find the pressure drop due to viscosity along
a5 m section pipe.
A. 40.2 Pa
C. 13.45 Pa
B.12.5 Pa
D. 45.77 Pa
Saluetion
4P L V
R2
4 1.005 x 10poise x
AP
(Sm)(0.2m/s)
poise
(1.0cm x lm/100 cm)
Ans. A
40.2Pa
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19. A 70.874 L/s (1S0 f3/min.) of water is flowing in a round pipe such that
(FluidMechanies 07)
23, A cylinder 10 m long and 2 m in diameter is suspended in air flowing at
the flow remains laminar. Considering that the critical Reynold's number
8 m/sec. The air flow is perpendicular to the longitudinal axis of the
to be 2000, what is the diameter ofthe pipe necessary to ensure laminar
cylinder. The density of air is 1.225 kg/m, and the coefficient of drag of
the cylinder is 1.3. What is the drag on the cylinder?
flow. (Note: kinematic viscosity of water is 4,75 x 10-5 ft/s)
C. 12.5 ft
D. 37.5 ft
A. 33.50 ft
B. 41.7 ft
Sel.lhon
Re
VD
A. 0.31 kN
C. 1.0kN
B. 0.85 kN
D. 2.3kN
Selutan
tere V
HK
I50/min (D
2000=
(10m)(2m)8m/s
/D-)(mi60s)n
=
1019.2N=101 kN
Ans. C
4.75 x10 s
D=33.51 t
24. Consider the holding tank shown. The tank voBume remains constant.
Ans. A
What is most nearly the velocity of the water exiting to the atrmosphere?
20. The pressure drop across a turbine is 30 psi. The flow rate is 60 gallons
per minute. Calculate the power output of the turbine.
A. 0.41 hp
C. 2.54 hp
B. 1.05 hpP
D. 6.30 hpP
Selulion
W= PV
=
psi)(60gal/nin
I
W 34650-btIbp-min
min33 000 Ibf-ft
I3
144 in
7481 gal
A. 3 m/s
B. 4 m/s
=1.05 hp
TFO
Ans. B
21.
Oil (specific gravity=0.8) at 3000 Pa flows at a constant rate of I m/s
through the circular nozzle shown. What is most nearly the net force
exerted by the joint to hold
the nozzle in place?
A. 140 KN
B. 240 kNN
C. 190 kN
D. 270 kN
D0.3m
V y2gh 29.81)2)m/s = 6.26m/s
Ans D
25. In the real flow of air (p=1.225 kg/m') around a cylinder, the circulation
is calculated to be 3.97 m/s. If the free stream velocity is 30 m/s, what is
the lift generaied per mietcr length of the cylinder?
A 150 N/m
naze|o.08m
Sels.tien
C. 5 m/s
D.6 m/s
C.170 N/m
D. 200 N/m
B. 160 N/m
D-0.06m
Solution
F=pv
F-01.25197mA0m/s) =145.8975
By balanceofforces:
FaF+mV-V
where:F pA
m
Solving for V,
14.15m/s
4(0.3m)
A
Ims
4(0.06m)
Ans. A
26. A 65 mm radius cylinder shown below rotates at 3600 revolutions per
minute. Air is flowing past the cylinder at 30 m/s. How much is the lift
the
unit length? The density
is 1.225
=353.68 m/s
CEB
Solving for m:
m=Po-(10kg/mo
s mA)-800Mg/s
Thus:
(3000Pa)(0.3m)+800
N/m
cylinder per
of air
kg/m
A.190 N/m
B. 220 N/m
C. 290 N/m
353.68-14.15
D. 370N/m
S
rpm
F= 271836.5 N 271.8 KN
Ans D
m/s
22. What is the terminal velocity of a 50 mmn diameter solid aluminun sphere
falling in air? Assume that the sphere has a coefficient of drag of 0.5, the
density of aluminum is 2650 kg/m', and the density of air is 1.225 kg/
A. 25 m/ sec
B. 53 m/sec
C. 88m/sec
D. 130 m / sec
Solution :
F=Lpvl
F-(11.225kg/m"\(30 m/s)(2x)(65mm)
Solutien:
3600 min1000mm
mmin 2
2mg
Pa(A)C)
m=pV 2650
F
Im
I000mun
2(0.1734ke)9.8Im/
225 kg/m3\(a10025m) (05)
B
where T 2r
= 01734 kg
53.2m/s
367.79 N/m
Ans. D
27. The low rate of water through a cast iron pipe is 20 m/min. The
diameter of the pipe is 0.3 m, and the coefficient of friction is f = 0.0173.
What is the pressure drop over a 30 m length of pipe?
A. 9.8 kPa
C. 17 kPa
B. 13 kPa
D. 19kPa
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P yhf
C. the fluid must be inviscid
D. all of the above
fLV
where: hf=
2gD
Solving for V:
Seletion :
v-9 20m/min (Imin
A
60s
= 4.716m/s
Valid for Bernouli
All of the above
ns. D
AnS.
4(0.3m)
thus:
P -9.800173/(30m)(4.716m/s)?
29.81m/2o.3m)
31. A jet of velocity Vjet. Cross-sectional area Ajer. and density Pje impinges
on a reversing vane and is turned through an angle of 180°. The vane is
moving with velocity Vvane in the direction of the original jet. What is the
19.24kPa
force, Fvame exerted on the vane by the water?
Ans.D
(jeTa*)
F
28. What is the hydraulic radius of the channel shown?
Ver-Vwone
A. 0.33 m
B. 0.43m
C.0.49 m
D.1.5m
A. 2p A
C. 2p AV.
B. pAV
D.
2p A. (V.-V.
m
Soletion
Fz mAV
Soluton:
Fz PA(av)
Solving for d:
F 2pA Vievane
Ans
h 2.6m
By Ratio and Proportion
So.
32. A pressurized tank contains a fluid with a density of 1300 kg/m. The
pressure in the air space above the fluid is 700 kPa Fluid exits to the
h-d
3
atmosphere from opening 3
an
d=1.732 m
m m1732m) 0.43m
nearly the exit velocity. v?
A. 11 m/s
m
below the fluid surface. What is most
C. 31 m/s
D. 52 m/s
B. 22 ms
2(2m)+Im+ 3m
Salulion
Ans.B
V2gb
29. The upper plate is fixed, wbile the lower plate moves in the positive
x
where b, =2t -Paiatm
Pe)
direction at 0.5 m/s. The plate separation is 0.001 m, the fluid viscosity
is 7x 10 Pa.s, and the velocity profile is linear. Calculate the shear stress,
So,
Ty in themoving fluid
CEBU V=/2(9.81m/s2
3ml01325Pa +700000Pa
V 31.30m/s
v
A. 0.05 Pa
C. 0.25 Pa
B. 0.15 Pa
D.0.35 Pa
0.5 m/s
Ans. C
33. What is the head loss of water flowing through a horizontal pipe if the
is 1.03 kPa, the gage pressure at point 2
gage pressure at point
downstream is 1.00 kPa, and the velocity is constant?
A. 3.1 x 10m
B. 3.1x10m
C. 2.3x10m
D. 2..3 m
Solubon :
Sottion
AP 103-100 kPa
T
3
9.81kN/m
0.001m
0.35Pa
Ans. D
30. Under which of the following econditions is Bernoulli"'s cquation valid?
A. all points evaluated must be on the same streamline
B. the fluid must be incompressible
Ans. A
3.06 x10
m
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34. The density of air flowing in a duct is I.15kg/m'. A pitot tube is placed
in the duct is measured with a wall tap at A(6x10° Pa)and pressure gage
at B(7x103 Pa). Use the gage readings to determine the veocity of the
air.
A. 42 m/s
C.I10 m/s
D.150 m/s
B. 102 m/s
39. One could expect the possibility of Froude number similarity in all of the
following cases except:
A. motion of a fluid jet
B. flow over spillways
C.surge and flood waves
D
subsonic air foils
Selution:
Salukion:
V 2ghT
Froude o. except > subsonic airfoils
where h,=
Ans. D
pg
7000-6000Pa
V 29.81m/s2
(L 15kg/m.sim/")
= 41.7 m/s
40. The fact that a fluid's velocity increases as the cross sectional area of the
pipe through which it flow decreases is due to :
A. Bermoull's equation
A
35. Determine the average velocity through a circular scction in which the
velocity distributionisgiven as V =V1-(t/,)The distribution
the continuity equation
the momentum equation
the perfect gas law
Solution :
is symmetric with respect to the longitudinal axis, r = 0. r0 is the outer
radius and the vmax is the velocity along the longitudinal axis.
A. V 4
C. V.2
B. Va3
B.
C.
D.
Vt A>continuity
Ans. B
D. V
41. When a falling object reaches a speed at which the drag force equals its
weight, it has achieved:
Slidion
Vave
TEFO
VdA
A.
Mach one
B.
a laminar boundary layer
C.
a turbulent boundary layer
D.
terminal velocity
Seltion :
F=WTerminal velocity
Ans. D
2max(
42. How does the Reynolds number of a 1/15 scale model relate to the
Reynolds number of a dimensionally similar prototype?
Ans. C
A. They areboth equal
36. If a 1/3 horsepower pump runs for 20 minutes, what is the energy used?
A. 0.06 ergs
C.0.30 MJU
B.
B. The Reynolds number of the prototype is 15 times lower
C. The Reyolds number of the prototype is 15 times lower
D. The Reynolds number of the model is a function of the velocity ratio.
D.0.11kW xh
0.25 kW
Solukon
Relate of Reynolds to model
Soluhan
Both equal
Ans. A
E= P
(0.746kWY 60sec
Ihp
Imin
E 298.4 kJ = 0.3 MJ
CE
Ans.C
37. Under what conditions is mass conserved in fluid flow?
C. The flow is adiabatic
A. The fluid is baratropic
D. It is always conserved
B. The flow is isentropic.
43. Fluid flows at 5m/s in a Scm diameter pipe section. The section is
connected to a 10 cm diameter section. At most nearly what velocity does
the fluid flow in the 10 cm section?
A. 1.00 m/s
C.2.50 cms
B. 1.25 m/s
D.10.0 cmvs
Solution :
AA
Solukion
()-(107
V =1.25m/s
mass is conserved > always
Ans.D
38. One could expect the possibility of Froude number similarity in all of the
followingcases except:
A.
B.
C.
D.
surface ships
surface wave motion
flow over weirs
closed pipe turbulent pipe tlow
Selukon
Froude no. except> closed pipe
Ans.D
=(B,)% - (D,)%
Ans. B
44. A venture meter installed horizontally is used to measure to flow of water
in a pipe. The area ratio, A2/44. of the meter is O.50 and the velocity
through the throat of the meter is 3m/s. What is the most nearly the
pressure differential across the venture meter?
A. 1.5 kPa
B. 2.3 KPa
Solulion
C.3.5 kPa
D.6.8 kPa
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49. What is the hydraulic radius of the trapezoidal(isosceles) irrigation canal
of bases 5 m and I1 cm respectively with depth of 4m?
A. 1.63 m
C.2.13 m
D4.00 m
B. 2.00 m
By Bernoulli's Eqn.
Selut
2gC,
Sor
Anow
(m/|1-(0s
hPwctted
Ans. B
9810N/m a981m/ (098)
-P2=3514.16Pa
»
3.5 kPa
AnsC
45. The 8 cm x 12 cm rectangular flume is filled to the three-quarters of its
height. What is most nearly the hydraulic radius of the flow?
A.
B.
C.3.0 cm
1.5 cm
2.5 cm
D.5.0 cm
[01+5)04)]n2
2(5)+5 m
2.13 m
50. A venture meter installed horizontally is used to measure to flow of water
in a pipe. The area ratio, A2/A1, of the meter is 0.S0 and the velocity
through the throat of the meter is 3 m/s. What is the most nearly the
pressure differential across the venture meter?
C. 3.5 kPa
A. 1.5 kPa
D. 6.8 kPa
B. 200 kPa
Setuen
By Bermoulls.
Seluion
.ow(8)(12)(3/4) cm
3 cm
Pw
282
Ans.C
46. A waterfall has a total drop of 15m and a flow rate 2 m/s. Most nearly
what theoretical power is available?
A. 294 Kw
C439 kWN
B. 375 kW
D.750 kW
Sa
Gm/)|1-(0.3
9810 N/m a981m/098
-P23514.16 Pa 3.5 kPa
Ans C
Selue
P=0h 9.8IN/w2m°s|(05 m)
=
294.3kw
Ans. A
47. To what height will 20°C ethyl alcohol(surface tension 0.0227 N/m,
contact angle (0, specific heat 0.68 kcal/kg°C, density 0.79 g/cm*) rise
is a 0.25 mm internal diameter glass capillary tube ? The density of the
alcohol is 790 kp/m.
A. 0.12 m
C.o.12 m
D.0.47 m
B. 0.047 m
51. A waterfall has a total drop of 15 m and a flow 2m'/s.Most nearly what
theoretical power is available?
A. 294 kW
B. 375 kW
C. 439 kW
D.750 kW
Solaton
P=öQh
P-981N/)2m4Ju5m)
P 294.3kW
Ans.A
Soln-ke
h=ocos8
d
4(0.0227 N/m)cos 0°
h
1000mm
9im/27901e/m* )(025mm)
0.047 m
Im
B
48. The diameter of a water pipe gradually changes from Scm at point A to
15 cm at point B. Point A is 5 m lower than point B. The pressure is 700
kPa at point A and 664 kPa at point B. Friction between the water and
the pipe wall is negligible. What is the rate of discharge at point B?
C.o.010m/s
A. 0.0035 m'/s.
B. 0.0064 m'/s.
52. A sliding-plate (50 cm x 25 cm) viscometer is used to measure the
viscosity of a Newionian fluid( I mm thick). A force of 25 N is required
to keep the top plate moving at a constant velocity of 5 m/s. What is the
viscosity of the fluid?
A. 0.005 N. s/m2
C.0.2 N. s/m2
B. 0.04 N s/m*
D. 5.0 N. s/m2
Sdukon :
2SN
D.0.018 m/s.
100em
Im
(50cm)(25cm)
lion:
0.04
By Bernoulli's Eqn.
Ans. B
++Z,
where: V = Q/A
8
53. A 2 mm (inside diameter ) glass tube is placed in a container of
mercury.
An angle of 40° is measured are 13550 kg/m and 37.5 x m2 N/m.
40
40
700
9.81
z(oos
2(9.81)
5m
664(0.15)
9.81
2(9.81)
respectively How high will the mercury rise or be depressed in the tube
as a result of capillary action?
+0
A.4.3 mm
B. -1.6 mm
Q0.010 m s
C
An
H Imm000mum
Im
lution
C.4.2 mmn
D.6.4 mm
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58. The coefficient of velocity is equal to the
A. Product of the coefficient of discharge and the coefficient of
contraction
B. Actual velocity divided by the theoretical velocity
C. Sum of the coefficient of discharge and the coefficient of
contraction
D. Difference of the coefficient of discharge and the coeficient
of contraction
4GCOSU
h-
&d
437.5x104 N/m |cos140 (1000mm
h=713550kg/m(981m/s )(2mam) Im
h 4.32 mm(depressed)
Ans.A
Selfon
54. A nuclear submarine is capable of a top underwater specd of 65 km/hr.
How fast would a 1/20 scale model of the submarine have to be moved
through a testing pool filled with seawater for the forces on the submarine
and model to be dimensionally similar?
A. 0.90 m/s
C.180 m/s
B. 18 m/s
D. 360 m/s
Solulion:
model=20
CyVA/
Ans.B
59. In parallel pipe system originating and terminating in common junctions.
A. mass flows through each branch are equal
B. pressure drops through each branch are equal
C. lengths of each branch are equal
D. flow areas of each branch are equal
Slution
model
20(65kph) m s
kph)
Parallel systems > pressure drops through each branch
361.1 Imps
Ans. B
Ans.D
55. Fluid flows at 5 m/s in a 5 cm diameter pipe section. The section is
connected to a 10 cm diameter section. At most nearly what velocity does
the fluid fow in the 10 cm section?
A. 1.00 m/s
C.2.50 cm/s
B. 1.25 m/s
D.10.0 cm/s
60. Venturi meters, pitot static gauges, orifice meters, flow nozzles, and
differential manometers ali depend upon the relationship between:
A. flow velocity and friction
B. Now velocity and pressure
C. friction and pressure
D. pressure and mass flow
Sel-kion
Venturimeters >low velocity and pressure
Solutiom
Ans.B
(Scm) (5 m/s)(10cm)(",)
61. Expansion factors take into account the :
V=1.25m/s
Ans.B
S6. The diameter of a pipe at the larger end is 0.50 m and at the end smaller
end is 0.20 m. the larger and smaller ends are located 7 meters and 3
meters respectively, from the datum line. f at the larger end, the velocity
is 1.2 meters per second and the pressure is 5200 kN/m2, compute the
pressure at the snmaller end.
A 5211.84 kPa
C4352.45 kPa
B. 5642.56 kPa
D.3452.45 kPa
ali
CE
C.
D.
changes in diameters of a converging pipe
effects of compressibility
Soltor"
Expansion factors ->compressibility
Ans.D
62.
matching of scale model and full scake results for
The
phenomena with a free surface requires equality of
-
A.
B.
Reynolds number
Froude number
a
fluid
dynanic
C. Weber number
D. Cauchy number
Selulion
63. The matching of scale model and full scale prototype results for a fluid
(0.50m)(0.2m/s)=(0.20m) (2))
dynamic phenomena involving surface tension requires equality of
V-7.5m/s
A.
B.
Then,
9.81N/m 219.81m/s
small effect of friction and turbulence of the orifice
Ans. B
Dv-DV2
(1.2 m/s
area of the vena contracta
B.
Matching scale to full model > froude
At Q-02
5200 kPa
A.
7m=
2
(7.5m/s)
9.81N/m 2/9.81m/
P= 5211.835 kPa
Ans. A
+
Reynolds number
Froude number
C. Weber number
D. Cauchy number
Seluton
Matching scale to full model involving surface tension > Reynolds
Ans. A
64. All of the following are forms of drag on a body moving through a fluid
except
57. The coefficient if discharge is the ratio of the :
A. area of vena contracta to the orifice area
B. actual discharge to the theoretical discharge
A.
B.
skin friction
profile drag
C. wake drag
D. d' Alembert's paradox drag
C. actual velocity to the theoretical velocity
Setution ?
D. effective head to the actual head
Forms of drag except >d Alembert's
Selion
Cp=Q,/0,
Ans. B
Ans. D
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changes in viscosity with changes in temperature?
A. Viscosity index
C. Coefficient of viscosity
B. Viscosity ratio
D. Viscosity factor
Solukon:
where: V=A
Fluid's sensitivity to change > vis. index
Ans. A
D
002 m
66. Which of the following ratios describes Reynolds number?
A. Inertial forces / Viscous forces
B. Drag forces/ Buoyant forces
C. Buoyant forces / Inertial forces
D. Viscous forces/ Drag forces
0.02m
7
m) a/4(008m
29.8Im/s
4(004
+0-1.5 mn
-P 104.02 kPa
Ans. B
Selukion
Re =F/F
AnsA
67. What is the classification of the fluid flow if the fluid travels parallel to
the adjacent layers and the paths of the individual paricles do not cross
each other?
A. Steady flow
C. Laminar flow
B. Unifom flow
D. Turbulent flow
Soluion
Travels in adjacent Laminar
Ans. C
68. What is the reciprocal of absolute viscosity?
C. Compressibility
A.Viscosity gradient
D. Viscosity index
B.Fluidity
Soluion :
P Qhen
10s00W=981(320m)0.8)
m
Q-3.93506 (1o001/m)
FOR
Q= 3935.06 L/s
Ans.A
74. A sealed tank containing seawater to a height of 12 m also contains air
above the water at gage pressure of 5 atm Water flows out from the
bottom through a small hole. Calculate the efflux speed of the
Selukiow
Reciprocal ofabs vis.
Ans. B
73. Find the volune flow rate of water in L/s if the power developed under a
head of 320 m is 10,500 kW and the hydraulic efficiency is 85%.
A.3.935
C. 3.271
D. 3,721
B.3.293
Fluidity
69. A vena contracta in a fluid jet issuing through a hole in a plate is localed
pproximately:
water.Note: pa
1.03x 103 kg/m
A.34.92 m/s
C. 20.45 m/s
D. 3545 m/s
B.45.24 m/s
Sdekon
A. 10 diameters downstream of the hole
B. at jet's minimum diameter
C. at the orifice minimum diameter
V=2gT
D.
ve9.81m/s12m
1.03 10kg/m (931m/)
at the orifice maximu m diameter
Solukion
Vena Contractajet minimum diameter
Ans. B
70. Which of thefollowing is the other name of velocity gradient?
C. rate of shear formation
A. strain rate
D. All of these
B. shear rate
Solukie :
Velocity gradientall
Ans.D
where: h= hz
5 atm(101325 Pa/atm)
V 34.92m/s
Ans.A
75. Water leaves a fuucet with a downward velocity of 3 m/s. As the water
falls below the faucet it accelerates with acceleration g. The cross
sectional area of the water stream leaving the faucet is 1.0 cm2. What is
the cross-sectional area of the stream 0.50 m below the faucet.
A.0.69 cm
C. 0.57 cm
B.0.45 cm
D. 0.25 cm
Selution
Solving for the velocity 0.50m below the faucet,
71. Alcohol finds use in manometers as :
A. it provides a suitable meniscus for the inclined tube
B. its density being less can provide longer length for a pressure
difference, thus more accuracy can be obtained
C. A and B above are comect
D. Cheap and easily avail1ble
v-(Bm/29s1m/A0.s0m)
V4.337m/s
Then,
Solution :
Alcohol in manometers > A andB
AnsC
12.
Acylindrical pipe with water flowing downward at 0.02 m'/s having top
diameter of 0.08, botom diameter of 0.04 m and height of 1.5 m. Find
the pressure between the pipe.
A. 94.05 kPa
C. 124.07 kPa
B. 104.06 kPa
D. 134.10 kPa
Sole-ton:
AA2
lcm 3 m/s -(A2)(4.37 m/s)
Ag 0.692 cm
Aas A
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76. A hose shoots water straight up a distance of 2.5 m. The end opening on
the hose has an area of 0.75 cm2. How much water comes out in min?
C. 20.5 iters
A.31.5 liters
Re
D. 130.5 liters
B.41.5 liters
vD
K
R.
Soluion:
Q= Av where v =/2gz
D
where
P
)-3.0x10*
1000
Ans. A
81. The jet discharges water at the rate of 0.10 m3/s and at a speed of 18 m/s
to stationary plate. Determine the force on the plate.
Q=31.516L/min
A.2800 N
B. 2000 N
Ans.A
77. A conical reducing sections connects an existent 10.16 cm diameter
Selution
pipeline with a new 5.08 cm diameter line. At 689.30 kPa static pressure
under no-1ow conditions, what is the tensile force is exerted on the
connectors at joint A assuming no end restraint from the pipe.
A.4.19 kN
C. 3.23 kN
F=pAv
B.5.12 kN
where: A
D. 4.15 kN
D. 2500 N
0.0056 m2
V18
thus;
Solulion :
F-00ks/mo.056msv
F P(AA) where A-D
F 4.19 kN
low under pressure ?
C. 38 ft
D. 35.80 ft
A.0.007 f
B.0.647
78. An oil flowing at
0.001
rale
has a kinematic
of 2x 10-5
What is the centerline velocity?
m3/sthroughi an 8 cm diamcter pipe
m2/s and anspecific gravity of 0.85
A.0.398 m/s
C. 0.235 m/s
D. 0.547 m/s
B.0.678 m/s
Salution
LV
where:
V =2
2gD
0.03(
Solution i
gul/munJ(ift/7481gal)
(60/mnin)(/4(17/12A) =37.77fn/mile
232.2/s )(07/12 n)(lmile/5280 f)
AV
0.001m
18144N
82. What is the expected head loss per mile of a closed circular pipe with 17
in. inside diameter friction factor of 0.03 when 3300 galvmin of water
NTUTEF
Ans. A
the of
viscosity
-
An C
F689.30BPa(10.16cm)-(5.08cmIm
Ji0ocm)
Q
C. 1800 N
8 emy (1O m
ns. C
V 0.199m/s
83. A 150 mm diameter pipe carries 81.3 L/s of water. The pipe branches into
For centerline velocity:
two pipes one is 50 mm in diameter and the other is 75 mm. What is the
max
2V=2(0.199 m/s) =0.398m/s
velocity in 75 mm pipe if the velocity of the flow in the 50 mm pipe is
10 m/s?
Ans. A
A. 13.96 m/s
C. 17.25 ms
D. 19.43 m/s
B.15.67 m/s
79. At a height of 10,000 m (33,000 ft ) above the sea level atmospheric
pressure is about 210 mm of Hg. What is the resultant normal force on a
600 cm2 window of an airplane flying atthis height when thehydrostatic
conditions and a pressure inside the plane of 760 mm of mercury and
density of mercury is 13,600 kg/m3 ?
C. 5.721 kN
A.4.403 kN
D. 2.741 kN
B.3.407 kN
Soluhion
992
where
Q1A
2= A22
s1000L41000
4{1000
Ans.A
(760 mmHg -210 mnHg)(600 cm2
1O1.325 kPa ( Im
760 mmHg Ji00em
FR 4 4 kN
Ans.A
84. A gas ows through a square conduit, at the entrance the conduit sides
are 10 cm. the velocity is 7.55 m/s, and the gas mass density is 1.09
kg/m3. At the exit, he conduit sides are 25 cm, and the velocity of the
flow is 2.02 m/s. Find the density of the gas at the exit section considering8
that the gas is compressible.
A.0.6598 kg/n
80. A submarine is 100 m long. The shape of its hull is roughly cylindrical
with a diamcter of 15 m. When it is submerged, it cruisesat a speed of
about 40 knots or approximately 20 m/s. Compute the Reynolds nuber,
if the viscosity is 1.0 x 10-3 Pa.s.
A.3x 10*
C. 5x 10*
B.4 x 10*
D. 2.5 x 10
Solulion i
and
V,= 13.96m/s
R cabinatmcabinaunA
R
Soletion i
B.0.6851 kg/n
Soluthon
C. 0.6518 kg/m*
D. 0.6185 kg/m'
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89. A scuba diver at a depth of 60 m notices the bubbles he exhales have
diameters of I cm. Assume the surface tension and water temperature remain
relatively constant. What is the depth if the diameter is 0.50 cm ?
A 540 cn
C. 120 cm
D. 480 cm
B. 320 cm
By Continuity eq.
m2
PA P2A2
(1.09kg/ma0cm) (2.55m/s)=o2(25cm)*(2.02m/s)
Sel-tien
P20.65 184kg/m3
cm
480 cm
0.50 cm
Ans.C
85. A hose shoots water straight up for a distance of 2.5 m. The end opening
on the hose has an area of 0.75 cm2. How much water come out in 1hour
C. 1.67 m
A.1.89 m3
B.0.78 m
D. 2.56 m
Solulion:
Q AV where: V =2gZ
Ans. D
90. A scuba diver at a depth of 60 m notices the bubbles he exhales have
diameters of I cm. Assume the surface tension and water temperature
bubble at 60m
relatively constant. What is the pressure
remain
depth?
A. 540 kPa
of the
C. 720 kPa
B. 320 kPa
D. 690 kPa
QA/2gz
o-(075am
00cm)
Selu-fion
im/2j2sm)
Pyh+ P9.81(60)+101 690 kPa
Ans. D
Q=1.891 m
Ans. A
91. What is the kinetic energy of 20°C water flowing in a5 cm pipe at 5 m/s?
C. 115 JAkg
D. 9.5 Jkg
A. 12.5 Jkg
86. How high does
stands on a day
pressure is 98.6 kPa considering that the specific gravity of mercury is
13.6.
mercury barometer
A.739 mm
when atmospheric
C760 mnm
D. 540 mnm
B.400 mm
B. 10.5 Jkg
NSTE
=12.5 1g
2
Ans. D
Seluien
760 mmHg
98.6 kPa
101.325 KPa
92. Ammonia at 140 kPa and 13°C (p = 0.988 kg/m) flows through a pipe.
739.56 mmHg
nicromanometer measuring impact pressure shows 4.06
is the velocity oftheammonia in the pipe?
C. 34.54 m/s
A. 43,58 m/s
Ans.A
87. A 10liter of an incompressibleliquidexertsa force of 20Nat the earth's
P Payo8h=(1000)(9.81)(4.06)=39.83x10'Pa
moon. The gravitational acceleration on the surface of the moon is 1.67
P=140x10 Pa-1.013i0 Pa =38.7a10 Pa
B.
V2-
C.3.4 N
D46 N
0.78N
of water. What
D. 32.23 m/s
B. 47.83 ins
Saletios
surface. What force would 2.31of thisliquid exerts onthe surface of the
m/s2
A. 0.39 N
m
39.8310-38.7xd0
47.83 m/s
0.988
P
Ans.E
Sdition :
FpVg
20Np(10L)981m/
CEB
p 0204kg/L
At the moon:
F-pVe-020423167m/-0783N
Ans.B
93. What is the equivalent diameter of a partially full rectangular channel
whose width is 30 feet (9.0 m) and depth is 5.0 feet (.5m) ?
A. 4.5 m
C. 2.5 mn
D.5 m
B.4 m
Solekion
AhL
40.5N9)45m
L+ 2h 9+201.5)
88. A scuba diver at a depth of 200 feet (60 m) notices the bubbles he exhales
Ans. A
have dianmeters of l/2 inch ( l cm). Assume tbe surface tension and water
temperature remain relatively constant. What diameter bubble should be
expect at a depth of 50 feet (15 m)?
C. 2.301 cm
D. 1.203 cm
A. 1.587 cm
B. 1452 cm
94. Air flows in a pipe of 0.75 in2(4.8 cm2) area at 250 ful/sec ( 76 m/s). The
density of the air is 0.075 fbm/ft3 (1.2 kg/m3). If the flow splits and both
halves leave parallel to the plate, what is the force required to hold the
plate?
Soluion i
A.
3.33N
B. 6.66N
P yh
hd -hd
4-
60mlam)=
1.587em
ISm
F=miaV pV(V-V,)
PAM[o-V -pA(,)
-124uo"76
R3.33N
Ans. A
Ans. A
C. 4.5 N
D. 9N
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95. A uniform area water jt travels at 200 m/s and
3 m'/s. What is the
honzontal force acts on the water jet if it undergcxes a 0
urn
C. 0.80 MN
A. - 0.60 MN
B. -0.75 MN
D. 0.23 MN
100. A jet is discharged through a 25 cm-diameter orifice under constant head
of 0.64 m. The total discharge is 103 kg in 0 seconds. The jet is observed
to pass through a point 60m downward 1.2 m away from the vena contracta.
Compute the coefficient of velocity.
C. 0.982
A. 682
B. 0.968
Soluion
D. 0.819
Selulen
F m'AV=pvV-V
-1on
1.2
C, 2h2(064)(0.6)
o-
-0.6MN
= 0.968
Ans. B
Ans.A
96. A unifom area water jet travels at 600 fty/sec (200 m/s) and 100 ft /sec (
3 m'/s). What is the horizontal force acts on the water jet if it undergoes a
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180 turn
C.-0.6 MN
A. 14 MN
B.
D. 4.5 MN
1.2 MN
Seludion:
F =miaV = pV(-V,-V,)
COR
Ans C
97. A jet is discharged through a 25 cm-diameter orifice under constant head
of 0.64 m. The total discharge is 103 kg in 90 seconds. The jet is observed
to pass through a point 6m downward 1,2 m away from the vena contracta.
Compute the theoretical velocity
C. 2.54 in/s
A. 3.54 m/s
B. 1.56 m/s
D. 4.35 m/s
Setulian
V= 2gH(2x9.8ix0.64)=3.54m/s
Ans.
98. A jet is discharged through a 25 cm-diameter onifice under constant head
of 0.64 m. The total discharge is 103 kg in 90 seconds. The jet is observed
to pass through a point 60m downward 1.2 m away from the vena contracta.
Compute the theoretical discharge in kg.
A. 156 kg8
C. 245 Kg
B. 345 kg
D. 452 kg
Salutiamt
m, = VA,pt where:V = (2X9.81x0.64) =3.54m/s
m, = 3.54(0.25) |(1000)(0) = 156 k
Ans. A
99. A jet is discharged through a 25 cm-diameter orifice under anstant head
of 0.64 m. The total dischurge is 103 kg in 90 seconds. The jet is observed
to pass through a poin 60m downward 1.2 m away from the vena contracta.
Computc the coefficient of contraction and the cocfficient of discharge.
A. 0.968
C 0.92
D. 0.69
B. 0.66
Sellion
m, =VA, p
where: V == (2x9.8100.64) = 3.54m/s
m, =3.540.25) (1000)90) =156kg
0.66
156
Ans. B
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