CIT – UNIVERSITY MECHANICAL ENGINEERING
1.
The 600 kg hammer of a pile drive
the piling head. If the hammer is
be its velocity at the instant it
Local g = 9.65 m/s2.
A. 6.21 m/s *
C. 1.2
B. 3.25 m/s
D. 4.5
Solution:
is lifted 2 m above
released, what will
strikes the piling?
ME COMPREHENSIVE EVALUATION COURSE 3
7.
m/s
m/s
A new temperature scale is to be used where freezing
and boiling temperature of water is at 100 deg.N and
400 deg. N respectively. Calculate the absolute zero
in degree N.
A. – 992.6 deg. N *
C. – 995.6 deg. N
B. – 932.7 deg. N
D. – 932.4 deg. N
Solution:
C
N-100
=
100
400
N = 4 C + 100
For: Absolute Zero
N =4(-273)+100 = -992.6 N
V = 2gh
= 2(9.65)(2)
= 6.21 m/s
2.
3.
In pump installations, what is referred as the vertical
distance from the water supply level to the pump
centerline wherein the pump is above the supply level?
A. Discharge head
C. Static suction head *
B. Suction head
D. Static discharge head
The 600 kg hammer of a pile drive
the piling head. If the hammer is
be its velocity at the instant it
Local g = 9.65 m/s2.
A. 6.21 m/s *
C. 1.2
B. 3.25 m/s
D. 4.5
Solution:
is lifted 2 m above
released, what will
strikes the piling?
m/s
m/s
V = 2gh
8.
9.
A closed vessel intended for use in heating water or
for application of heat to generate steam.
A. Intercooler
C. Sink
B. Water heater
D. Boiler *
An elastic sphere containing gas at 120 kPa has a
diameter of 1.0 m. Heating the sphere causes it to
expand to a diameter of 1.4 m. During the process the
pressure is proportional to the sphere
diameter.
Calculate the work done by the gas
A. 143.91 kJ
C. 154.5 Kj
B. 200.7 kJ
D. 133.91 kJ *
Solution:

= 15 1.4
= 2(9.65)(2)
W = 15 Df 4  Do 4
= 6.21 m/s
4.
Which of the following is an extensive property?
A. mass *
C. density
B. pressure
D. all of the above
5.
Calculate the thermal diffusivity of pure aluminum with
density of 2,702 kg/m3 , thermal conductivity of 237
W/m.K and specific heat of 0.903 kJ/kg.K.
A. 97.1 x 10-6 m2/s *
C. 14.9 x 10-6 m2/s
B. 23.25 x 10-6 m2/s
D. 34.5 x 10-6 m2/s
Solution:
 =
=
k
 Cp
237
(2702)(0.903)
= 97.1 x10-6 m/s2
6.
At what temperature wherein an oil of any grade becomes
cloudy and it freezes, thus its application is limited.
A. Cloud point *
C. Flash point
B. Pour point
D. Freezing point
4

 1.04

W = 133.91 kJ
10. What is
without
A. 1/2
B. 1/3
the lowest permissible water level of a boiler
internal furnace?
height of shell
C. 1/4 height of shell
height of shell * D. 1/5 of shell
11. Air is used in a Carnot engine where the volumes at
the beginning of the constant temperature heat addition
and end of the constant temperature heat rejection are
0.456 cm3 and 6.73 cm3 respectively.
Calculate the
thermal efficiency.
A. 0.667
C. 0.786
B. 0.656 *
D. 0.765
Solution:
DIAGNOSTIC EXAMINATION – SET A
e=1-
1
TL
TH
where:
k-1
V 
TH
=  4
TL
 V1 
subst:
e =1-
1.4-1
 6.573 
= 

 0.456 
 2.91
1
= 0.656
2.91
12. At ordinary temperature what substance will behave as
inert gas and will not react in the combustion process?
A. nitrogen *
C. sulfur
B. hydrogen
D. carbon
13. What is the lifting force in kN for a 10 m diameter
spherical balloon with helium inside at 101 kPa and
320 K surrounded by air at 101 Kpa and 298.15 K ?
A. 17.38 kN
C. 18.73 Kn
B. 5.28
kN *
D. 8.25 kN
Solution:
F =  a  He  V

 4
 0.00981 kN 
101
101
3
= 


   5  kg 
0.287(298.15)
2.077(320)
3
1 kg






= 5.28 kN
14. When the temperature of the surrounding is higher than
the blood temperature of human body then the transfer
of heat will take place only by
A. Convection
C. Radiation *
B. Cooling
D. Evaporation
15. The filament of a 100 W bulb maybe considered a
blackbody radiating into a black enclosure at 80 deg.
C. Considering only radiation, calculate the filament
temperature in deg. C if the filament diameter is 0.10
mm and the length is 6 cm.
A. 3109.97 deg. C
C. 3245.45 deg. C
B. 2837 deg. C
*
D. 2313.5 deg. C
Solution:

Q = 5.67 x 10-8A T14 -To4

2

 0.0001  4
 T  353
100 = 5.67 x 10-8  (0.0001)(0.06) 
4


T = 3109.97 K
T = 2837°C
16. Both Stirling and Ericsson engines are
A. internal combustion engines
B. external combustion engines *
C. Carnot engines
CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN!
CIT – UNIVERSITY MECHANICAL ENGINEERING
D.
Brayton engines
17. A circular chip ( k = 150 W/m.K) with a diameter 10 mm
and thickness 4 mm is embedded in a circuit board. Its
front surface is exposed to the flow of a coolant ( h
= 250 W/m2K) with temperature of 10 deg. C , while its
side and black surfaces are perfectly insulated. If at
any point in the chip the temperature must not exceed
90 deg. C, what is the steady state heat dissipation
of the chip ?
A. 2.86 W
C. 2.01 W
B. 1.56 W *
D. 1.74 W
Solution:
Q=
kAT
x
where:
Qconduction= Qconvection
kAT
= h A T
x
150(363 - Tf )
= 250 ( Tf - 283)
0.004
Tf = 3632.47 K
   0.012 
 363  362.47 
Q = 150 
4


Q = 1.56 W
18. In Stirling and Ericsson cycle, regeneration can
A. increase efficiency * C. decrease efficiency
B. control efficiency
D. limit efficiency
19. A 1 kg steel ( C = 0.5 kJ/kg.K) rivet cools from 800 K
to 300 K upon being installed in a riveted structure.
The entropy change in kJ/K of this rivet is:
A. -0.245
C. -0.631
B. -0.49
*
D. -0.546
Solution:
T 
ΔS = mC ln  2 
 T1 
 300 
ΔS = (1)(0.5) ln 
 = -0.49
 800 
20. Gauge cock in the boiler is designed to determine
A. level of steam
C. specific heat
B. level of water*
D. pressure
21. The heat pump has a performance factor of 8.0. If the
heat pump is used as a refrigerator, what is the
required horsepower per ton of refrigeration ?
A. 0.942
C. 0.765
B. 0.456
D. 0.673 *
Solution:
ME COMPREHENSIVE EVALUATION COURSE 3
Hp
=
TOR
where:
COP =
=
=
subst:
Hp
=
TOR
4.71
COP
DIAGNOSTIC EXAMINATION – SET A
A.
B.
PF - 1
8 -1
7
2.89
*
3.24
Solution:
2
C. 1.34
D. 3.21
Snet = SH  SL
where:
4.71
= 0.673
7
SL =
22. The thermal efficiency of gas-vapor cycle compared to
steam turbine or gas turbine is
A. Greater than *
C. The same
B. Less than
D. Less than 10%
23. Find the COP of the refrigerator whose energy supply
equals one-fourth the amount of heat it extracts.
A. 3
C. 5
B. 4 *
D. 2
Solution:
COP =
QL
Wnet
where:
1
Wnet = QL
4
subst:
QL
COP =
1/4 QL
COP = 4
24. The relative humidity becomes 100% and where the water
vapor starts to condense.
A. Critical point
C. Saturated point
B. Dew point *
D. Cloud point
25. If the specific heat at constant pressure for CO2 is
given as 0.201 Btu/lb-R, what is the value of the
specific heat at constant volume ?
A. 0.156 Btu/lb-R *
C. 0.435 Btu/lb-R
B. 0.365 Btu/lb-R
D. 0.435 Btu/lb-R
Solution:
Cv = Cp - R
= 0.201 -
1545
44(778)
= 0.156
QL
TL
SH =
4000
200+460
SL = 6.06
QH
TH
-4000
800+460
SH = - 3.17
=
=
thus:
ΔSnet = -3.17+6.06 = 2.89
28. Mr. De La Cruz wanted to buy a pump for his farm .What
is suitable for deepwell?
A. Reciprocating
C. Airlift
B. Hand lift
D. Centrifugal *
29. Air flows
in a duct at pressure of 150 kPa with a
velocity of 200 m/s. The temperature of the air is 310
K . Determine the isentropic stagnation temperature.
A. 320
C. 341
B. 332
*
D. 361
Solution:
V2
= Cp  T - To 
2000
210
2
= 1  T - 310
2000
T = 332.05 K
30. In a cooling tower, the water is cooled mainly by
A. Condensation
C. evaporation
B. convection *
D. conduction
31. A reverse Carnot cycle air refrigeration equipment has
a compressor working with a compression ratio of 12.
The temperature limits of the cycle are 300 K and 270
K. Determine the refrigerating effect of the unit.
A. 2.45 TR
C. 2.06 TR
B. 1.86 TR
D. 1.26 TR *
Solution:
26. In pipe specification, schedule number is used; when
the pipe is specified as “Schedule 80”, the pipe
corresponds to the
A. “extra standard” weight C. extra strong *
B. internal pressure
D. “old standard weight”
27. An amount of 4000 Btu of heat is transferred from a
reservoir at 800 deg.F to a reservoir at 200 deg. F.
Find the entropy change of the system.
CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN!
CIT – UNIVERSITY MECHANICAL ENGINEERING
ME COMPREHENSIVE EVALUATION COURSE 3
Q = COP(W)
where:
270
= 9
(300-270)
1
W=
= 0.497
1.4-1
12 1.4
COP =
subst:
Q = 9(0.497) = 4.42 kW = 1.26 TR
32. A hot block is cooled by blowing cool air over its top
surface. The heat that is first transferred to the air
layer close to the block is by conduction. It is
eventually carried away from the surface by
A. convection*
C. radiation
B. conduction
D. thermal radiation
33. A refrigeration system produces 20 kg/hr of ice from
water at 20 deg.C. Find the tonnage of the unit.
A. 0.66
*
C. 0.77
B. 0.55
D. 0.88
Solution:
Q = mh
where: h = 335 + 4.19 ( 20 - 0 )
h = 418.8 kJ/kg
then:
Q = 20(418.8) = 8376 kJ/kg
8376
TR =
= 0.66 tons
3.5(3600)
34. An engineer inspected an air-conditioning unit. He
found out that the unit does not produce any cooling
effect, however, the air-conditioning unit is running.
He checked the temperatures of the condenser and
evaporator and had the unit run. He found out that
there was no change in the temperature. What should he
do?
A. Replace fuse
C. Charge with new refrigerant *
B. Replace relay D. Adjust door seal
35. About 3 Hp per ton is required to maintain a
temperature of – 40 deg. C in a refrigerator. If the
refrigerator works on the reverse Carnot cycle,
determine the heat rejected to the sink per ton of
refrigeration.
A. 69.72 kCal/min
C. 81.61 kCal/min *
B. 70.24 kCal/min
D. 84.65 kCal/min
Solution:
Heat rejected to the sink = Heat extracted + Work required
QR = QE + W
where: QE  1 TR = 50 kCal/min
W = 3 Hp = 31.6 kCal/min
thus:
QR = 81.61 kCal/min.
36. A turbine pipe determined its “nominal” size refers to
A. inside diameter *
C. outside diameter
B. pipe wall thickness D. approximate size
37. Determine the mass of ice produced from water per day
for the following conditions: Water temperature 22 deg.
C, tonnage of the unit 150 tons, operating temperature
22 deg. C, tonnage of unit 150 tons, operating
temperatures – 5 deg. C and 28 deg. C, latent heat of
ice 330 kJ/kg.
A. 107,498 kg *
C. 134,112 kg
B. 120,465 kg
D. 140,362 kg
Solution:
RE
Q
where : RE = 150 TR = 525 kW
Q = 330 + 1 (4.19)(22-0) = 421.96 kJ/kg
thus:
525
m=
= 1.24 kg/s = 107,498 kg/day
421.96
m=
38. A cold storage is required to store 20 tons of fish.
The fish is supplied at a temperature os 30 deg.C .
The specific heat of fish above the freezing point is
2.93 kJ/kg.K. The specific heat of fish above the
freezing point is 2.93 kJ/kg.K. The specific heat of
fish below freezing point is 1.26 kJ.kg.K. The fish is
stored in cold storage that is maintained at -8 deg.
C. The freezing point of the fish is -4 deg. C. The
latent heat of solidification of the fish is 235 kJ/kg.
If the plant requires 75 kW to drive it, find the time
taken to achieve cooling. Assume the actual COP as 0.3
times the Carnot COP of the refrigerating plant.
A. 14.72 hrs
C. 10.41 hrs
B. 9.64 hrs
D. 12.03 hrs *
Solution:
DIAGNOSTIC EXAMINATION – SET A
3
Q
RE
where:
RE = (COP)W
= [ 0.3(6.97)] (75)
= 156.8 kW
Q = Q1 + Q2 + Q3
t=
=
(2.93)(303-269)  1.26(269  265)  235  20, 000
= 6.793 x 106 kJ
thus:
t =
6.793 x 106
= 43,320 seconds = 12.03 hrs
156.8
39. A research laboratory building is to be heated and
ventilated. Air is to be supplied to a room 12 m by 18
m from the outside at the rate of 1 m3/min air
replacement for each square meter of floor space. The
design condition include 20 deg. C room temperature
and – 20 deg. C outside air temperature. In addition
the pressure in the room is to be maintained at a
positive pressure of 7 kPa, to ensure that there will
be no air leakage into the laboratory. How much heat
would be required to condition the air for this room?
A. 177.11 kW
C. 168.7 Kw
B. 154.8 kW
D. 185.3 Kw *
Solution:
Q = mCp T
where:
m=
PV
108.325(216)
=
= 278 kg/min
RT
0.287(293)
Q = 278(1)(40)
= 11120 kJ/min
= 185.3 kW
40. The size of a steam reciprocating pumps is generally
designated by a three-digit number size as 646. The
first digit designates
A. stroke of the pump in inches
B. inside diameter of the steam cylinder measured in
inches*
C. percent clearance
D. number of cylinders
41. A refrigeration system produces 20 kg/hr of ice from
water at 20 deg. C. Find the tonnage of the unit.
A. 0.66
*
C. 0.77
B. 0.55
D. 0.88
Solution:
CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN!
CIT – UNIVERSITY MECHANICAL ENGINEERING
Q = mh
where:
h = 335 + 4.19 (20  0)
= 418.8 kJ/kg
then:
Q = 20 (418.8)
= 8376 kJ/hr
8376
TR =
= 0.66 tons
3.5(3600)
42. About 3 hp per ton is required to maintain a
temperature of – 40 deg. C in a refrigerator. If the
refrigerator works on the reverse carnot cycle,
determine the heat rejected to the sink per ton of
refrigeration.
A. 69.72 kCal/min
C. 81.61 kCal/min *
B. 70.44 kCal/min
D. 84.65 kCal/min
Solution:
QR = QE + W
where:
QE = 1 TR = 50 kCal/min.
W = 3 Hp = 31.6 kCal/min.
thus:
QR = 81.61 kCal/min
43. Determine the mass of ice produced from water per day
for the following conditions: water temperature 22 deg
C, tonnage of the unit 150 tons, operating temperatures
– 5 deg. C and 28 deg C, latent heat of ice 330 kJ/kg.
A. 107,498 kg *
C. 134,112 kg
B. 120,465 kg
D. 140,362 kg
Solution:
m=
RE
Q
where:
RE = 150 TOR = 525 kW
Q = 330 + 1(4.19)(22-0) = 421.96 kJ/kg
thus:
525
m=
= 1.24 kg/s = 107.498 kg/day
421.96
44. What should be the cooling requirement due to emission
of body to maintain a comfortable temperature in a
dance hall that had an attendance of 1500 people if it
has been determined that 75% of the people will be
dancing and others will be seated. Test have shown that
an adult will give off 71.8 W of sensible heat while
engaging in moderate dancing and 57.1 W of sensible
heat while sitting. The latent heat emissions for
similar situations have been found to equal 177.3 W
for dancers and 45.5 W for sitters.
ME COMPREHENSIVE EVALUATION COURSE 3
A.
B.
200 kW
267 kW
Solution:
C.
D.
301 Kw
319 Kw *
Q = 1125 ( 71.8 + 177.3 ) + 375 ( 57.1 + 45.4 )
= 318,676 W = 319 kW
45. A refrigerator is rated at a USA one ton capacity. It
maintains a cooling temperature of 4.4 deg. C (
evaporator
temperature).
A
refrigerant
with
a
refrigerating effect of 136 kJ/kg is in the condenser
just ahead of the expansion valve. If the refrigerant
vapor has a density of 19.80 kg/m3 , what should be
the capacity of the compressor?
A. 0.078 m3 / min *
C. 0.102 m3 / min
B. 0.091 m3 / min
D. 0.113 m3/min.
Solution:
DIAGNOSTIC EXAMINATION – SET A
QR
= COP
W
where: W = 3 Hp = 7635 Btu/hr
460
COP =
= 4.6
560 - 460
thus:
QR = 4.6(7635) = 35,100 Btu/hr
48. Twenty grams of Oxygen are compressed at constant
temperature of 30 deg. C to 5% of their original
volume. What work is done on the system in SI.
A. -2.516
C.-3.75
B. -2.615
D. -4.72 *
Solution:
V2
W = mRT ln ( ) = (0.02 kg) (
907(335)
Q=
= 3.52 kW
24(3600)
3.52 kW
m=
= 0.0259 kg/s
136 kJ/kg
0.0259 kg/s
V=
= 0.001308 m3 /s = 0.07848 m3 / min
19.8 kg/m3
46. An engine operating on a Carnot Cycle between
temperatures of 500 deg. C and 30 deg. C produces 50
kJ of work. What change in entropy occurs during the
heat rejection portion of the cycle ?
A. 106.4 J/K *
C. 120.5 J/K
B. 160.4 J/K
D. 102.5 J/K
Solution:
Q A - QR
Q
=
T
T
where:
QR = 50 kJ
S =
V1
kJ
kg−K
8.314
2(16)
) (30 + 273.15) ln(0.05)
W = −4.719 kJ
49. The increase of enthalpy of a certain gas is 141.9 KJ.
when the pressure increases from 103.448 kpa to1034.48
kpa and the volume decreases form 0.4722 cu. m to
0.0745 cu. M. Find he change of internal enthalpy.
A. 121.45
C. 141.5
B. 114.25 *
D. 154.2
Solution:
∆𝐻 = ∆𝑈 + (𝑃2 𝑉2 − 𝑃1 𝑉1 )
∆𝑈 = 141.9 𝑘𝐽 − [(1034.48)(0.0745) − (103.448)(0.4722)]
∆𝑈 = 114 𝑘𝐽
50. Foundations are preferably built of concrete in the
proportion of what measure of Portland cement: sand :
crushed stones?
A. 1:2:5
C. 2:4:6
B. 2:3:5
D. 1:2:4*
---NOTHING FOLLOWS ---
Q A = 50/e
773 - 303
= 0.6080
773
Q A = 50/0.6080 = 82.24
e=
thus:
S =
4
82.24 - 50
= 0.1064 kJ/K = 106.4 J/K
303
47. A 3 Hp refrigerator or heat pump operates between 0
deg F and 100 deg. F. The maximum theoretical heat that
can be transferred from the cold reservoir is nearest
to:
A. 1300 Btu/hr
C. 35000 Btu/hr *
B. 2300 Btu/hr
D. 43000 Btu/hr
Solution:
CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN! CIT-ME TOPS AGAIN!