APPLIED MECHANICAL ENGINEERING

(GENERAL SCIENCES)
APPLIED MECHANICAL ENGINEERING

1. The output power available and delivered to the switchboard is:

a. brake power c. conduction d. radiation

b. combined
power
2. Heat transfer due to density differential is:
a. convection b. nuclear c. conduction d. radiation
3. It is a type of heat exchanger wherein the steam is not mixed or contaminated with
cooling water in the condensing process.
a. jet condenser b. surface condenser c. closed condenser d. deaerator
4. A device that automatically allows accumulated liquid to pass from a higher pressure
to a lower pressure region.
a. pump b. valve c. trap d. compressor
5. It supply the required air combustion and to remove the product of combustion.
a. purging b. vacuum pump c. draft system d. soot blower
6. The natural direction of heat flow is from a low temperature reservoir to a high
temperature reservoir. The fact is incorporated in:
a. the first law of thermodynamics
b. the second law of thermodynamics
c. the law of refrigeration
d. the law of conservation of energy
7. An anergic system is one in which:
a. no heat enters or leaves the system
b. the system does no work nor is doing work on it
c. the temperature remains constant
d. the pressure remains constant
8. A heat exchanger that pre-heats feedwater using the heat of the flue gas is:
a. deaerator b. condenser c. superheater d. economizer
9. What does the area under the curve in the pV-diagram represents?
a. steady flow work b. non-flow work c. Flow work d. net work
10. The engine cycle operating on two adiabatic and two isometric processes is:
a. Rankine b. Carnot c. Otto d. Diesel
11. It is the lower temperature at which oil will flow under prescribes condition.
a. flash point b. pour point c. viscous d. none of these
12. It is refined petroleum naphtha which by its composition is suitable for use as a
carburetant in internal combustion engine.
a. diesel b. gasoline c. fuel oil d. kerosene
13. It is a hydrocarbon fluid of high ignition quality.
a. octane b. cetane c. methane d. ethane
14. A crack in the earth through which geothermal substance passes.
a. moderator b. fumarole c. reflector d. fuel core
15. What are the largest fossil-fuel energy resources in the world?
a. coal b. crude oil c. natural gas d. bio-gas
16. What is the condition of a fluid if its temperature is higher than the saturation
temperature of the existing pressure?
a. sub-cooled b. wet-mixture c. saturated d. superheated
17. The enthalpy of an ideal gas is a function of:
a. pressure b. volume c. temperature d. work

18. The process that has no work transfer is;

a. adiabatic b. quasistatic c. anergic d. isentropic
19. The theory of changing heat into mechanical work is;
a. inertia b. heat transfer c. thermodynamics d. joule
20. A substance that follows the Pv = mRT relation is:
a. vapour b. perfect gas c. liquid d. steam
21. The force of gravity per unit volume is known as;
a. density b. pressure c. gravity d. specific weight
22. It is the cycle usually used as a reference cycle in thermodynamics;
a. diesel b. otto c. carnot d. brayton
23. What cycle is used or patterned in the construction of a steam power plant?
a. thermal cycle b. diesel cycle c. carnot cycle d. rankine cycle
24. The internal combustion engine never works on______ cycles.
a. rankine b. reheat c. regenerative d. all of these
25. The force that tends to draw a body towards the centre about which it is rotating?
a. centrifugal b. centripetal c. internal d. external
26. What is the apparatus used in the analysis of exhaust gases?
a. orsat b. oxygen bomb c. calorimeter d. all of these
27. The ratio of the density of substance to the density of standard water:
a. relative density b. specific density c. weight density d. none
28. When the property of a substance ceases to change, the substance is said to be;
a. in solid state b. liquid state c. thermal equilibrium d. equilibrium
29. Temperature at which an oil gives off vapours that mixed with air and form an
inflammable mixture
a. fire point b. flash point c. pour point d. combustion point
30. Which of the following is not a viscosity rating:
a. stoke b. poise c. engler d. API
31. What do you call a small piece of energy?
a. potential b. kinetic c. stored d. quantum
32. The function of the carburetor on a gasoline engine is to:
a. filter the air
b. filter the fuel
c. mix the air and the gasoline properly
d. supply the proper fuel needed
33. Which of the following surfaces will absorb the greatest percentage of radiant energy:
a. black b. yellow c. white d. polished metal
34. One boiler horsepower is equivalent to:
a. 33,000Btu/hr b.33,480 c. 34,000 d. 34,500
35. The existence of ______ gas in the atmosphere causes a greenhouse effect.
a. CO b. CO2 c. CH4 d.all of these
36. It is the position of a piston in which it is furthest from the crankshaft
A. after top dead center C. bottom dead center
B. top dead center D. before bottom dead center
37. It is a device that heats the steam generated by the boiler again, increasing its thermal energy
and decreasing the chances that it will condense inside the turbine
A. superheater C. boiler drum
B. reheater D. economizer
38. These are energy sources which are not destroyed when their energy is harnessed.
A. chemical energy C. renewable energy
B. electrical energy D. solar energy
39. It is a heat exchanger which utilizes the heat of the flue gases to preheat the air needed for
combustion.
A. economizer C. feedwater heater
B. preheater D. superheater
40. Which of the following components does not belong to a gas turbine power plant?
a. compressor c. condenser
b. turbine d. combustion chamber

1. Calculate the energy transfer rate across 6 in wall of firebricks with a temperature difference
across the wall of 50°C. The thermal conductivity of the firebrick is 0.65 Btu/hr-ft-°F at the
temperature interest. (October ’94)
A) 285 W/m2 B) 369 C) 112 D) 429
Solution:
x = 6 in = 0.50 ft
(ta – tb) = 50C × 1.8 = 90°F
QC = [k A (ta – tb)] / x
QC / A = [0.65 (90)] / 0.50 = 117 Btu/hr-ft2
QC / A = 117 Btu/hr-ft2 = 369 W/m2

2. The sun generates 1 KW/m 2 when used as a source for solar collectors. A collector with an area
of 1 m2 heats water. The flow rate is 3.0 liters/min. What is the temperature rise in the water?
The specific heat of water is 4,200 J/kg -°C. (April ’97)
A) 4.8ºC B) 0.48 C) 0.56 D) 0.84
Solution:
Q = 1KW/m2 (1 m2) = 1,000W
m = 3 li/m2 x [1kg/li] x [min/60sec] = 0.05 kg/s
Q = m × cp × Δt
Δt = Q / m CP = 1000 / [0.05 × 4200] = 4.76°C

3. What is the temperature in degree C of 2 liters of water at 30 degree C after 500 calories of heat
have been added to? (April ’98)
A) 35.70ºC B) 30.25 C) 38.00 D) 39.75
Solution:
Q = m × cp × (t2 – t1)
0.500 Kcal (4.187 KJ/Kcal) = 2 liters (1kg/liter )(4.187 KJ/kg-°C)(t 2 – 30°C)
t2 = 30.25°C

4. At an average temperature of 100°C, hot air flows through a 2.5 m long tube with an inside
diameter of 50 mm. The temperature of the tube is 20°C along its entire length. Convective film
coefficient is 20.1 W/m2-°K. Determine the convective heat transfer from air to the tube. (April ‘
97)
A) 900W B) 909 C) 624 D) 632
Solution:
A = lateral heat transfer area = π × D × L
= π × (0.050m) × (2.5m) = 0.3927 m2
 QC = hC × A × (t2 – t1)
QC = 20.1W/m2-K × (0.3927m2 × (100 – 20)K
QC = 631.5 W

5. One kg of water initially at 15ºC is to be freeze at –3ºC. Calculate the total amount of heat to be
removed during the cooling process? Cpice = 0.5(Cpw)
A) 39.831KJ B) 403 C) 3983.1 D) 39,831
Solution:
Q1 = mC∆T = 1kg (4.187KJ/kg-K)(15 – 0)K = 62.8KJ
Q2 = m(Lf ) = 1kg (334KJ/kg) = 334KJ
Q3 = mC∆T = 1kg (0.5)(4.187)KJ/kg-K [0 – (– 3)] = 6.28KJ
QT = 403KJ

6. Calculate the enthalpy in KJ of 1.50 kg of fluid that occupies a volume of 0.565 m 3 if the internal
energy is 555.60 Kcal / kg and the pressure is 2 atm.
A) 2,603.7 KJ B) 3,603.7 C) 4,603.7 D) 5,603.7
Solution:
h = u + pv
= [555.6 kcal/kg x (1.055KJ/0.252kcal)] + 2atm(101.325)(0.565/1.5)m 3/kg
= 2402.35 KJ/kg
H = mh = 1.5(2402.35) = 3,603.5KJ

7. A volume of 400 cc of air is measured at a pressure of 740 mmHg abs and a temperature of 18°C.
What will be the volume at 760 mmHg and 0°C?
A) 376 cc B) 326 C) 356 D) 365
Solution:
P1V1 / T1 = P2V2 / T2
740(400) / [18+273] = 760 V2 / [0+273] V2 = 365 cc

8. When the pressure of an ideal gas is doubled while the absolute temperature is halved, the volume
is:
A) quadrupled B) doubled C) halved D) quartered.
Solution:
P1V1 / T1 = P2V2 / T2
V2 / V1 = P1T2 / P2T1 = P1(0.5T1) / 2P1T1 = (0.5)(0.5) = 0.25

9. Three resistors with 4, 5 and 6 ohms respectively are connected in parallel. Calculate the total
resistance in the circuit.
A) 6.122 B) 1.622 C) 2.661 D) 1.226
Solution:
1 / RT = 1/R1 + 1/R2 + 1/R3
= ¼ + 1/5 + 1/6
= 37/60
RT = 60/37 = 1.622 ohms

10. What current would flow for three hours through a resistance of 50 ohms to produce enough heat
to raise the temperature of ten kg water from the freezing point to boiling point?
A) 2.78amp B) 7.6 C) 0.776 D) 776
Solution:
Q = mC∆T = 10kg (4.187KJ/kg-K)(100K) = 4,187 KJ
Heat rate = 4,187KJ / 3hrs = 1,396 KJ/hr = 0.388 KW = 388 W
Therefore;
I = √ P / R = √388W / 50ohms = 2.78 amp
11. How many 100-W lamps connected in parallel can be placed in a 230 volts circuit, which is
protected by a 30-amp fuse?
A) 69 B) 70 C) 71 D) 72
Solution:
P = E x I = 230volts x 30amp = 6,900 watts
NL = 6900 / 100 = 69

12. A 12-V automotive storage battery is charged with a constant current of 10 amp for 3 hours.
Determine the amount of energy supplied to the battery in KW-hr.
A) 0.33 B) 0.36 C) 0.39 D) 0.42
Solution:
E = 12Volts x 10amp x 3hrs = 360watt-hrs = 0.36 KW-hr

13. Electrical resistance of 7 ohms and 11 ohms are connected in parallel and the combination of
which is then connected in series with a resistance of 15 ohms and a source of 220 volts.
Calculate the total current flowing in the circuit.
A) 0.57amp B) 11.41 C) 10.41 D) 0.057
Solution:
RT = 15 + [1 / (1/7 + 1/11)] = 19.28 ohms
I = E / R = 220volts / 19.28ohms = 11.41 amp

14. A 50 mm dia. pipe is 15 m long extends vertically downward from the bottom of an elevated tank
and discharges into air. When the water in the tank is 3 m from the entrance to the pipe, what is
the discharge in liters/sec?
A) 36.88L/s B) 38.86 C) 68.38 D) 63.88
Solution:
Vel = √2gh = √2(9.81)18 = 18.783 m/s
Q = V x A = (18.783) x 0.7854 x (0.05)2
= 0.03688 m3/s
= 36.88 liters / s

15. An opened topped cylindrical tank with oil (S.G. = 0.8) has a circular base 10m in diameter when
filled to a height of 8m. Calculate the force exerted in its base.
A) 4,296KN B) 4,926 C) 4,629 D) 4,962
Solution:
F = pressure x area
= (hγ) A
= 8m x [0.8(1000kg/m3)(9.81m/s2)] x [0.7854(10m)2]
= 4,926,028.8 N

16. If the velocity in a 300mm pipe is 0.50 m/s, determine the discharge in a 75mm diameter jet
attached to the pipe.
A) 33.5L/s B) 35.3 C) 53.3 D) 55.3
Solution:
Q = Vel1 x Area1 = Vel2 x Area2
= 0.50 m /s x 0.7854 x 0.3m2
= 0.03534 m3/sec
= 35.3 L/s

17. A wheel starts from rest and acquires a speed of 500 rad/sec in 15 seconds. Calculate the
approximate number of turns made by the wheel.
A) 119.4 B) 1,194 C) 11,940 D) 119,400
Solution:
NT = 500rad/s x 15 sec x 1rev / 2πrad
 = 1,194 rev

18. A ball dropped from the roof of a building 40 m high will hit the ground with a velocity of:
A) 20 m/s B) 28 C) 38 D) 40
Solution:
V = √2gh = √2(9.81)(40) = 28m/s

19. One kg-mole of oxygen gas has a molecular mass of:

A) 16kg B) 32kg C) 16g D) 32g
Solution:
1 kg-mole = 32kg 1lb-mole = 32lb 1g-mole = 32gram

20. Ten liters of 25% salt solution and 15 liters of 35% salt solution are poured into a drum originally
containing 30 liters of 10% salt solution. What is the percent concentration of salt in the mixture?
A) 19.55% B) 22.15% C) 27.05% D) 25.72%
Solution:
25% + 35% + 10% = x%

10 15 30 55

0.25(10) + 0.35(15) + 0.10(30) = X (55)

x = 19.55%

21. Ethane gas burns according to the equation, 2C2H6 + 7 O2 → 4CO2 + 6H2O.
What mass of CO2, measured at standard temperature and pressure, is formed for each gram-mole
of C2H6 burned?
A) 82.4 grams B) 88 C) 880 D) 180

2C2H6 → 4CO2 C2H6 → 2CO2 2g-mole [44 gm/g-mole] = 88gm

22. Express, X = 0.351351351…. into fractional number

A) 351/999 B) 351/100 C) 99/351 D) 351/98

23. Express, X = 0.353535 into fractional number

A) 35/99 B) 35/100 C) 99/35 D) 35/98
24. Express, X = 0.77777777 into fractional number :
A) X = 6/9 B) X = 7/ 10 C) X = 7/9 D) X = 6/10
x  2 2 2  .......
25. Evaluate:
A) X = 1 B) X = 2 C) X = 3 D) X= 4