Thermodynamics Questions and Answers

Thermodynamics Questions and Answers

1. Which of the following variables controls the
physical properties of a perfect gas
(a) pressure
(b) temperature
(c) volume
(d) all of the above
(e) atomic mass.
Ans: d
2. Which of the following laws is applicable for the
behavior of a perfect gas
(a) Boyle's law
(b) Charles'law
(c) Gay-Lussac law
(d) all of the above
(e) Joule's law.
Ans: d
3. The unit of temperature in S.I. units is
(a) Centigrade
(b) Celsius
(c) Fahrenheit
(d) Kelvin
(e) Rankine.
Ans: d
4. The unit of mass in S.I. units is
(a) kilogram
(b) gram
(c) tonne
(d) quintal
(e) newton.
Ans: a
5. The unit of time in S.I. units is
(a) second
(b) minute
(c) hour
(d) day
(e) year.
Ans: a
6. The unit of length in S.I. units is
(a) meter
(b) centimeter
(c) kilometer
(d) millimeter.
Ans: a
7. The unit of energy in S.I. units is
(a) watt
(b) joule
(c) joule/s
(d) joule/m
(e) joule m.
Ans: b
8. According to Gay-Lussac law for a perfect gas,
the absolute pressure of given mass varies directly
as
(a) temperature
(b) absolute
(c) absolute temperature, if volume is kept constant
(d) volume, if temperature is kept constant
(e) remains constant,if volume and temperature are
kept constant.
Ans: c
9. An ideal gas as compared to a real gas at very
high pressure occupies
(a) more volume
(b) less volume
(c) same volume
(d) unpredictable behaviour
(e) no such correlation.
Ans: a
10. General gas equation is
(a) PV=nRT
(b) PV=mRT
(d) PV = C
(c) PV=KiRT
(e) Cp-Cv = Wj
Ans: b
11. According to Dalton's law, the total pres sure of
the mixture of gases is equal to
(a) greater of the partial pressures of all
(b) average of the partial pressures of all
(c) sum of the partial pressures of all
(d) sum of the partial pressures of all divided by
average molecular weight
(e) atmospheric pressure.
Ans: c
12. Which of the following can be regarded as gas
so that gas laws could be applicable, within the
commonly encountered temperature limits.
(a) 02, N2, steam, C02
(b) Oz, N2, water vapour
(c) S02, NH3, C02, moisture
(d) 02, N2, H2, air
(e) steam vapours, H2, C02.
Ans: d
13. The unit of pressure in S.I. units is
(a) kg/cm2
(b) mm of water column
(c) pascal
(d) dynes per square cm
(e) bars
Ans: c
14. A closed system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) mass crosses the boundary but not the energy
(c) neither mass nor energy crosses the
boundaries of the system
(d) both energy and mass cross the boundaries of
the system
(e) thermodynamic reactions take place.
Ans: a
15. Temperature of a gas is produced due to
(a) its heating value
(b) kinetic energy of molecules
(c) repulsion of molecules
(d) attraction of molecules
(e) surface tension of molecules.
Ans: b
16. According to kinetic theory of gases, the
absolute zero temperature is attained when
(a) volume of the gas is zero
(b) pressure of the gas is zero
(c) kinetic energy of the molecules is zero
(d) specific heat of gas is zero
(e) mass is zero.
Ans: c
17. Kinetic theory of gases assumes that the
collisions between the molecules are
(a) perfectly elastic
(b) perfectly inelastic
(c) partly elastic
(d) partly inelastic
(e) partly elastic and partly inelastic.
Ans: a
18. The pressure'of a gas in terms of its mean
kinetic energy per unit volume E is equal to
(a) E/3
(b) E/2
(c) 3E/4
(d)2E/3
(e) 5E/4.
Ans: d
19. Kinetic energy of the molecules in terms of
absolute temperature (T) is proportional to
(a) T
(b) j
(c) J2
(d) Vr
(e) 1/Vr.
Ans: a
20. Superheated vapour behaves
(a) exactly as gas
(b) as steam
(c) as ordinary vapour
(d) approximately as a gas
(e) as average of gas and vapour.
Ans: d
21. Absolute zero pressure will occur
(a) at sea level
(b) at the center of the earth
(c) when molecular momentum of the system
becomes zero
(d) under vacuum conditions
(e) at a temperature of - 273 °K
Ans: c
22. No liquid can exist as liquid at
(a) - 273 °K
(b) vacuum
(c) zero pressure
(d) centre of earth
(e) in space.
Ans: c
23. The unit of power in S.I. units is
(a) newton
(b) pascal
(c) erg
(d) watt
(e) joule.
Ans: d
24. The condition of perfect vacuum, i.e., absolute
zero pressure can be attained at
(a) a temperature of - 273.16°C
(b) a temperature of 0°C
(c) a temperature of 273 °K
(d) a negative pressure and 0°C temperature
(e) can't be attained.
Ans: a
25. Intensive property of a system is one whose
value
(a) depends on the mass of the system, like volume
(b) does not depend on the mass of the system, like
temperature, pressure, etc.
(c) is not dependent on the path followed but on the
state
(d) is dependent on the path followed and not on the
state
(e) remains constant.
Ans: b
26. Specific heat of air at constant pressure is equal
to
(a) 0.17
(b) 0.21
(c) 0.24
(d) 1.0
(e) 1.41
Ans: c
27. Characteristic gas constant of a gas is equal to
(a) C/Cv
(b) Cv/Cp
(c) Cp - Cv
(d) Cp + Cv
(e) Cp x Cv
Ans: c
28. The behaviour of gases can be fully determined
by
(a) 1 law
(b) 2 laws
(c) 3 laws
(d) 4 laws
Ans: d
29. The ratio of two specific heats of air is equal to
(a) 0.17
(b) 0.24
(c) 0.1
(d) 1.41
(e) 2.71.
Ans: d
30. Boyle's law i.e. pV = constant is applicable to
gases under
(a) all ranges of pressures
(b) only small range of pressures
(c) high range of pressures
(d) steady change of pressures
(e) atmospheric conditions.
Ans: b
31. Which law states that the internal energy of a
gas is a function of temperature
(a) Charles' law
(b) Joule's law
(c) Regnault's law
(d) Boyle's law
(e) there is no such law.
Ans: b
32. The same volume of all gases would represent
their
(a) densities
(b) specific weights
(c) molecular weights
(d) gas characteristic constants
(e) specific gravities.
Ans: c
33. Which law states that the specific heat of a gas
remains constant at all temperatures and pressures
(a) Charles' Law
(b) Joule's Law
(c) Regnault's Law
(d) Boyle's Law
(e) there is no such law.
Ans: c
34. An open system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) neither mass nor energy crosses the
boundaries of the system
(c) both energy and mass cross the boundaries of
the system
(d) mass crosses the boundary but not the energy
(e) thermodynamic reactions do not occur.
Ans: c
35. According to which law, all perfect gases
change in volume by l/273th of their original volume
at 0°C for every 1°C change in temperature when
pressure remains constant
(a) Joule's law
(b) Boyle's law
(c) Regnault's law
(d) Gay-Lussac law
(e) Charles' law.
Ans: e
36. Gases have
(a) only one value of specific heat
(b) two values of specific heat
(c) three values of specific heat
(d) no value of specific heat
(e) under some conditions one value and
sometimes two values of specific heat.
Ans: b
37. According to Avogadro's Hypothesis
(a) the molecular weights of all the perfect gases
occupy the same volume under same conditions of
pressure and temperature
(b) the sum of partial pressure of mixture of two
gases is sum of the two
(c) product of the gas constant and the molecular
weight of an ideal gas is constant
(d) gases have two values of specific heat
(e) all systems can be regarded as closed systems.
Ans: a
38. Extensive property of a system is one whose
value
(a) depends on the mass of the system like volume
(b) does not depend on the mass of the system, like
temperature, pressure, etc.
(c) is not dependent on the path followed but on the
state
(d) is dependent on the path followed and not on the
state
(e) is always constant.
Ans: a
39. Work done in a free expansion process is
(a) + ve
(b) -ve
(c) zero
(d) maximum
(e) minimum.
Ans: c
40. The statement that molecular weights of all
gases occupy the same volume is known as
(a) Avogadro's hypothesis
(b) Dalton's law
(c) Gas law
(d) Law of thermodynamics
(e) Joule's law.
Ans: a
41. To convert volumetric analysis to gravimetric
analysis, the relative volume of each constituent of
the flue gases is
(a) divided by its molecular weight
(b) multiplied by its molecular weight
(c) multiplied by its density
(d) multiplied by its specific weight
(e) divided by its specific weight.
Ans: b
42. If a gas is heated against a pressure, keeping
the volume constant, then work done will be equal
to
(a) + v
(b) - ve
(c) zero
(d) pressure x volume
(e) any where between zero and infinity.
Ans: c
43. An isolated system is one in which
(a) mass does not cross boundaries of the system,
though energy may do so
(b) neither mass nor energy crosses the
boundaries of the system
(c) both energy and mass cross the boundaries of
the system
(d) mass crosses the boundary but not the energy
(e) thermodynamic reactions do not occur.
Ans: b
44. Properties of substances like pressure,
temperature and density, in thermodynamic
coordinates are
(a) path functions
(b) point functions
(c) cyclic functions
(d) real functions
(e) thermodynamic functions.
Ans: b
45. Which of the following quantities is not the
property of the system
(a) pressure
(b) temperature
(c) specific volume
(d) heat
(e) density.
Ans: d
46. According to Avogadro's law, for a given
pressure and temperature, each molecule of a gas
(a) occupies volume proportional to its molecular
weight
(b) occupies volume proportional to its specific
weight
(c) occupies volume inversely proportional to its
molecular weight
(d) occupies volume inversely proportional to its
specific weight
(e) occupies same volume.
Ans: e
47. Mixture of ice and water form a
(a) closed system
(b) open system
(c) isolated system
(d) heterogeneous system
(e) thermodynamic system.
Ans: d
48. Which of the following is the property of a
system
(a) pressure and temperature
(b) internal energy
(c) volume and density
(d) enthalpy and entropy
(e) all of the above.
Ans: e
49. On weight basis, air contains following parts of
oxygen
(a) 21
(b) 23
(c) 25
(d) 73
(e) 79.
Ans: b
50. Which of the following is not the intensive
property
(a) pressure
(b) temperature
(c) density
(d) heat
(e) specific volume.
Ans: d
51. Which of the following items is not a path
function
(a) heat
(b) work
(c) kinetic energy
(d) vdp
(e) thermal conductivity.
Ans: e
52. Work done in an adiabatic process between a
given pair of end states depends on
(a) the end states only
(b) particular adiabatic process
(c) the value of index n
(d) the value of heattransferred
(e) mass of the system.
Ans: a
53. Heat and work are
(a) point functions
(b) system properties
(c) path functions
(d) intensive properties
(e) extensive properties.
Ans: c
54. Which of the following parameters is constant
for a mole for most of the gases at a given
temperature and pressure
(a) enthalpy
(b) volume
(c) mass
(d) entropy
(e) specific volume.
Ans: b
55. The value of n = 1 in the polytropic process
indicates it to be
(a) reversible process
(b) isothermal process
(c) adiabatic process
(d) irreversible process
(e) free expansion process.
Ans: b
56. Solids and liquids have
(a) one value of specific heat (ft) two values of
specific heat
(c) three values of specific heat
(d) no value of specific heat
(e) one value under some conditions and two
values under other conditions.
Ans: a
57. A perfect gas at 27°C is heated at constant
pressure till its volume is double. The final
temperature is
(a) 54°C
(b) 327°C
(c)  108°C
(d) 654°C
(e) 600°C
Ans: b
58. Curve A in Fig. 1.1 compared to curves B and C
shows the following type of expansion
(a) pV"=C
(b) isothermal
(c) adiabatic
(d) free expansion
(e) throttling.
Ans: b
59. If value of n is infinitely large in a polytropic
process pV" = C, then the process is known as
constant
(a) volume
(b) pressure
(c) temperature
(d) enthalpy
(e) entropy.
Ans: a
60. The index of compression n tends to reach ratio
of specific heats y when
(a) flow is uniform and steady
(b) process is isentropic
(c) process is isothermal
(d) process is isentropic and specific heat does not
change with temperature
(e) process is isentropic and specific heat changes
with temperature.
Ans: d
61. Change in enthalpy of a system is the heat
supplied at
(a) constant pressure
(b) constant temperature
(c) constant volume
(d) constant entropy
(e) N.T.P. condition.
Ans: a
62. The term N.T.P. stands for
(a) nominal temperature and pressure
(b) natural temperature and pressure
(c) normal temperature and pressure
(d) normal thermodynamic practice
(e) normal thermodynamic pressure.
Ans: c
63. A heat exchange process in which the product of
pressure and volume remains constant is known as
(a) heat exchange process
(b) throttling process
(c) isentropic process
(d) adiabatic process
(e) hyperbolic process.
Ans: e
64. In an isothermal process, the internal energy of
gas molecules
(a) increases
(b) decreases
(c) remains constant
(d) may increase/decrease depending on the
properties of gas
(e) shows unpredictable behaviour.
Ans: c
65. Zeroth law of thermodynamics
(a) deals with conversion of mass and energy
(b) deals with reversibility and irreversibility of
process
(c) states that if two systems are both in
equilibrium with a third system, they are in thermal
equilibrium with each other
(d) deals with heat engines
(e) does not exist.
Ans: c
66. If a certain amount of dry ice is mixed with
same amount of water at 80°C, the final
temperature of mixture will be
(a) 80°C
(b) 0°C
(c) 40°C
(d) 20°C
(e) 60°C.
Ans: b
67. The basis for measuring thermodynamic
property of temperature is given by
(a) zeroth law of thermodynamics
(b) first law of thermodynamics
(c) second law of thermodynamics
(d) third law of thermodynamics
(e) Avogadro's hypothesis.
Ans: a
68. One watt is equal to
(a) 1 Nm/s
(b) 1 N/mt
(c) 1 Nm/hr
(d) 1 kNm/hr
(e) 1 kNm/mt.
Ans: a
69. Work done is zero for the following process
(a) constant volume
(b) free expansion
(c) throttling
(d) all Of the above
(e) none of the above.
Ans: d
70. For which of the following substances, the gas
laws can be used with minimum error
(a) dry steam
(b) wet steam
(c) saturated steam
(d) superheated steam
(e) steam at atmospheric pressure.
Ans: d
71. In a non-flow reversible process for which p =
(- 3V+ 15) x 105N/m2,V changes from 1 m to 2
m3. The work done will be about
(a) 100 xlOO5 joules
(b) lxlO5 joules
(c) 10 xlO5 joules
(d) 10 xlO5 kilo joules
(e) 10xl04ki\ojoules.
Ans: c
72. The value of the product of molecular weight and
the gas characteristic constant for all the gases in
M.K.S. unit is
(a) 29.27 kgfm/mol°K
(b) 8314kgfm/mol°K
(c) 848kgfm/mol°K
(d) 427kgfm/mol°K
(e) 735 kgfm/mol°K.
Ans: c
73. On volume basis, air contains following parts of
oxygen
(a) 21
(b) 23
(c) 25
(d) 77
(e) 79.
Ans: a
74. Universal gas constant is defined as equal to
product of the molecular weight of the gas and
(a) specific heat at constant pressure
(b) specific heat at constant volume
(c) ratio of two specific heats
(d) gas constant
(e) unity.
Ans: d
75. The value of the product of molecular weight and
the gas characteristic constant for all the gases in
S.I. units is
(a) 29.27 J/kmol°K
(b) 83.14J/kmol°K
(c) 848J/kmol°K
(d) All J/kmol °K
(e) 735 J/kmol °K.
Ans: b
76. For which of the following substances, the
internal energy and enthalpy are the functions of
temperature only
(a) any gas
(b) saturated steam
(c) water
(d) perfect gas
(e) superheated steam.
Ans: d
77. In a free expansion process
(a) work done is zero
(b) heat transfer is zero
(c) both (a) and (b) above
(d) work done is zero but heat increases
(e) work done is zero but heat decreases.
Ans: c
78. If a gas vapour is allowed to expand through a
very minute aperture, then such a process is known
as
(a) free expansion
(b) hyperbolic expansion
(c) adiabatic expansion
(d) parabolic expansion
(e) throttling.
Ans: e
79. The specific heat of air increases with increase
in
(a) temperature
(b) pressure
(c) both pressure and temperature
(d) variation of its constituents
(e) air flow
Ans: a
80. If a fluid expands suddenly into vacuum through
an orifice of large dimension, then such a process is
called
(a) free expansion
(b) hyperbolic expansion
(c) adiabatic expansion
(d) parabolic expansion
(e) throttling.
Ans: a
81. Which of the following processes are
thermodynamically reversible
(a) throttling
(b) free expansion
(c) constant volume and constant pressure
(d) hyperbolic and pV = C
(e) isothermal and adiabatic.
Ans: e
82. Which of the following processes is irreversible
process
(a) isothermal
(b) adiabatic
(c) throttling
(d) all of the above
(e) none of the above.
Ans: c
83. In order that a cycle be reversible, following
must be satisfied
(a) free expansion or friction resisted expansion/
compression process should not be encountered
(b) when heat is being absorbed, temperature of hot
source and working sub¬stance should be same
(c) when beat is being rejected, temperature of cold
source and working sub-stance should be same
(d) all of the above
(e) none of the above.
Ans: d
84. For a thermodynamic process to be reversible,
the temperature difference between hot body and
working substance should be
(a) zero
(b) minimum
(d) maximum
(d) infinity
(e) there is no such criterion.
Ans: a
85. Minimum work in compressor is possible when
the value of adiabatic index n is equal to
(a) 0.75
(b) 1
(c) 1.27
(d) 1.35
(e) 2.
Ans: b
86. Molecular volume of any perfect gas at 600 x
103 N/m2 and 27°C will be
(a) 4.17m3/kgmol
(b) 400 m3/kg mol
(c) 0.15 m3/kg mol
(d) 41.7 m3/kg mol
(e) 417m3/kgmol.
Ans: a
87. A gas is compressed in a cylinder by a movable
piston to a volume one-half its original volume.
During the process 300 kJ heat left the gas and
internal energy remained same. The work done on
gas in Nm will be
(a) 300 Nm
(b) 300,000 Nm
(c) 30 Nm
(d) 3000 Nm
(e) 30,000 Nm.
Ans: b
88. The more effective way of increasing efficiency
of Carnot engine is to
(a) increase higher temperature
(b) decrease higher temperature
(c) increase lower temperature
(d) decrease lower temperature
(e) keep lower temperature constant.
Ans: d
89. Entropy change depends on
(a) heat transfer
(b) mass transfer
(c) change of temperature
(d) thermodynamic state
(e) change of pressure and volume.
Ans: a
90. For reversible adiabatic process, change in
entropy is
(a) maximum
(b) minimum
(c) zero
(d) unpredictable
(e) negative.
Ans: c
91. Isochoric process is one in which
(a) free expansion takes place
(b) very little mechanical work is done by the
system
(c) no mechanical work is done by the system
(d) all parameters remain constant
(e) mass and energy transfer do not take place.
Ans: c
92. According to first law of thermodynamics
(a) work done by a system is equal to heat
transferred by the system
(b) total internal energy of  a system during a
process remains constant
(c) internal energy, enthalpy and entropy during a
process remain constant
(d) total energy of a system remains constant
(e) entropy of a system remains constant.
Ans: d
93. Energy can neither be created nor destroyed but
can be converted from one form to other is inferred
from
(a) zeroth low of thermodynamic
(b) first law of thermodynamics
(c) second law to thermodynamics
(d) basic law of thermodynamics
(e) claussius statement.
Ans: b
94. First law of thermodynamics furnishes the
relationship between
(a) heat and work
(b) heat, work and properties of the system
(c) various properties of the system
(d) various thermodynamic processes
(e) heat and internal energy.
Ans: b
95. Change in enthalpy in a closed system is equal
to heat transferred if the reversible process takes
place at constant
(a) pressure
(b) temperature
(c) volume
(d) internal energy
(e) entropy.
Ans: a
96. In an isothermal process, the internal energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: c
97. Change in internal energy in a closed system is
equal to heat transferred if the reversible process
takes place at constant
(a) pressure
(b) temperature
(c) volume
(d) internal energy
(e) entropy.
Ans: c
98. According to first law of thermodynamics
(a) mass and energy are mutually convertible
(b) Carnot engine is most efficient
(c) heat and work are mutually convertible
(d) mass and light are mutually convertible
(e) heat flows from hot substance to cold
substance.
Ans: c
99. Total heat of a substance is also known as
(a) internal energy
(b) entropy
(c) thermal capacity
(d) enthalpy
(e) thermalconductance.
Ans: d
100. First law of thermodynamics
(a) enables to determine change in internal energy
of the system
(b) does not help to predict whether the system will
or not undergo a change
(c) does not enable to determine change in entropy
(d) provides relationship between heat, work and
internal energy
(e) all of the above.
Ans: e
101. Addition of heat at constant pressure to a gas
results in
(a) raising its temperature
(b) raising its pressure
(c) raising its volume
(d) raising its temperature and doing external work
(e) doing external work.
Ans: d
102. Carnot cycle has maximum efficiency for
(a) reversible engine
(b) irreversible engine
(c) new engine
(d) petrol engine
(e) diesel engine.
Ans: a
103. Measurement of temperature is based on
(a) thermodynamic properties
(b) zeroth law of thermodynamics
(c) first law of thermodynamics
(d) second law of thermodynamics
(e) joule's law.
Ans: b
104. Carnot cycle efficiency depends upon
(a) properties of the medium/substance used
(b) condition of engine
(c) working condition
(d) temperature range of operation
(e) effectiveness of insulating material around the
engine.
Ans: d
105. Carnot cycle efficiency is maximum when
(a) initial temperature is 0°K
(b) final temperature is 0°K
(c) difference between initial and final temperature
is 0°K
(d) final temperature is 0°C
(e) initial temperature is minimum possible.
Ans: b
106. An engine operates between temperatures of
900°Kandr2 and another engine between T2 and
400°K For both to do equal work, value of T2 will be
(a) 650°K
(b) 600°K
(c) 625°K
(d) 700°K
(e) 750°K.
Ans: a
107. If heat be exchanged in a reversible manner,
which of the following property of the working
substance will change accordingly
(a) temperature
(b) enthalpy
(c) internal energy
(d) entropy
(e) all of the above.
Ans: d
108. If a system after undergoing a series of
processes, returns to the initial state then
(a) process is thermodynamically in equilibrium
(b) process is executed in closed system cycle
(c) its entropy will change due to irreversibility
(d) sum of heat and work transfer will be zero
(e) no work will be done by the system.
Ans: d
109. Which of the following represents the perpetual
motion of the first kind
(a) engine with 100% thermal efficiency
(b) a fully reversible engine
(c) transfer of heat energy from low temperature
source to high temperature source
(d) a machine that continuously creates its own
energy
(e) production of energy by temperature differential
in sea water at different levels.
Ans:
110. An actual engine is to be designed having
same efficiency as the Carnot cycle. Such a
proposition is
(a) feasible
(b) impossible
(c) possible
(d) possible, but with lot of sophistications
(e) desirable.
Ans: d
112. A manufacturer claims to have a heat engine
capable of developing 20 h.p. by receiving heat input
of 400 kcal/mt and working between the
temperature limits of 227° C and 27° C. His claim is
(a) justified
(b) not possible
(c) may be possible with lot of sophistications
(d) cost will be very high
(e) theroretically possible.
Ans: b
113. In a Carnot cycle, heat is transferred at
(a) constant pressure
(b) constant volume
(c) constant temperature
(d) constant enthaply
(e) any one of the above.
Ans: c
114. A diathermic wall is one which
(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) does not exist.
Ans: b
115. An adiabatic wall is one which
(a) prevents thermal interaction
(b) permits thermal interaction
(c) encourages thermal interaction
(d) discourages thermal interaction
(e) dos not exist.
Ans: a
116. The door of a running refrigerator inside a
room was left open. Which of the following
statements is correct?
(a) The room will be cooled to the temperature
inside the refrigerator.
(b) The room will be cooled very slightly.
(c) The room will be gradually warmed up.
(d) The temperature of the air in room will remain
unaffected.
(e) any one of above is possible depending on the
capacity.
Ans: c
117. Compressed air coming out from a punctured
football
(a) becomes hotter
(b) becomes cooler1
(c) remains at the same temperature
(d) may become hotter or cooler depend-ing upon
the humidity of the surround¬ing air
(e) attains atmospheric temperature.
Ans: b
118. Water contained in a beaker can be made to
boil by passing steam through it
(a) at atmospheric pressure
(b) at a pressure below the firuosphejric pressure
(c) at a pressure greater than atmospheric
pressure
(d) any pressure
(e) not possible.
Ans: c
119. During throttling process
(a) heat exchange does not take place
(b) no work is done by expanding steam
(c) there is no change of internal energy of steam
(d) all of the above
(e) entropy decreases.
Ans: d
120. The energy of molecular motion appears as
(a) heat
(b) potential energy
(c) surface tension
(d) friction
(e) increase in pressure.
Ans: a
121. A sudden fall in the barometer reading is a
sign of approaching
(a) fine weather
(b) rains
(c) storm
(d) cold wave
(e) hot wave.
Ans: c
122. The unit'of universal gas constant is
(a) watts/°K
(b) dynes/°C
(c) ergscm/°K
(d)erg/°K
(e) none of the above.
Ans: d
123. Calorie is a measure of
(a) specific heat
(b) quantity of heat
(c) thermal capacity
(d)entropy
(e) work.
Ans: b
124. I kgf/cm2 is equal to
(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) lOOmmHg.
Ans: c
125. Barometric pressure is equal to
(a) 760 mm Hg
(b) zero mm Hg
(c) 735.6 mm Hg
(d) 1 mm Hg
(e) 100mm Hg.
Ans: a
126. One barometric pressure or 1 atmospheric
pressure is equal to
(a) 1 kgf/cnr2
(b) 1.033 kgf/cm2
(c) 0 kgf/cm2
(d) 1.0197 kgf/cm2
(e) 100 kgf/cm2.
Ans: b
127. The first law of thermodynamics is the law of
(a) conservation of mass
(b) conservation of energy
(c) conservation of momentum
(d) conservation of heat
(e) conservation of temperature.
Ans: b
128. A perpetual motion machine is
(a) a thermodynamic machine
(b) a non-thermodynamic machine
(c) a hypothetical machine
(d) a hypothetical machine whose opera-tion would
violate the laws of thermodynamics
(e) an inefficient machine.
Ans: d
129. Kelvin Planck's law deals with
(a) conservation of heat
(b) conservation of work
(c) conversion of heat into work
(d) conversion fo work into heat
(e) conservation of mass.
Ans: c
130. According to Clausis statement of second law
of thermodynamics
(a) heat can't be transferred from low temperature
source to high temperature source
(b) heat can be transferred for low temperature to
high temperature source by using refrigeration
cycle.
(c) heat can be transferred from low temperature to
high temperature source if COP of process is more
than unity
(d) heat can't be transferred from low temperature
to high temperature source without the aid of
external energy
(e) all of the above.
Ans: d
131. Thermal power plant works on
(a) Carnot cycle
(b) Joule cycle
(d) Rankine cycle
(d) Otto cycle
(e) Brayton cycle.
Ans: c
132. Which of the following is an irreversible cycle
(a) carnot
(b) Stirling
(c) ericsson
(d) all of the above
(e) none of the above.
Ans: e
133. Otto cycle consists of following four processes
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pres-sures
(e) none of the above.
Ans: b
134. The efficiency of a Carnot engine depends on
(a) working substance
(b) design of engine
(c) size of engine
(d) type of fuel fired
(e) temperatures of source and sink.
Ans: e
135. For same compression ratio and for same heat
added
(a) Otto cycle is more efficient than Diesel cycle
(b) Diesel cycle is more efficient than Otto cycle
(c) efficiency depends on other factors
(d) both Otto and Diesel cycles are equally efficient
(e) none of the above.
Ans: a
136. The efficiency of Carnot cycle is maximum for
(a) gas engine
(b) well lubricated engine
(c) petrol engine
(d) steam engine
(e) reversible engine.
Ans: e
137. Carnot cycle is
(a) a reversible cycle (ft) an irreversible cycle
(c) a semi-reversible cycle
(d) a quasi static cycle
(e) an adiabatic irreversible cycle.
Ans: a
138. Diesel cycle consists of following four
processes
(a) two isothermals and two isentropics
(b) two isentropics, and two constant volumes.
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pressures
(e) none of the above.
Ans: c
139. If both Stirling and Carnot cycles operate within
the same temperature limits, then efficiency of
Stirling cycle as compared to Carnot cycle
(a) more
(b) less
(c) equal
(d) depends on other factors
(e) none of the above.
Ans: c
140. Stirling and Ericsson cycles are
(a) reversible cycles
(b) irreversible cycles
(c) quasi-static cycles
(d) semi-reversible cycles
(e) adiabatic irreversible cycles.
Ans: a
141. A cycle consisting of two adiabatics and two
constant pressure processes is known as
(a) Otto cycle
(b) Ericsson cycle
(c) Joule cycle
(d) Stirling cycle
(e) Atkinson cycle.
Ans: c
142. Reversed joule cycle is called
(a) Carnot cycle
(b) Rankine cycle
(c) Brayton cycle
(d) Bell Coleman cycle
(e) Dual cycle.
Ans: c
143. Brayton cycle consists' of following four
processes
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pres-sures
(e) none of the above.
Ans: d
144. Which of the following cycles is not a
reversible cycle
(a) Carnot
(b) Ericsson
(c) Stirling
(d) Joule
(e) none of the above.
Ans: e
145. The cycle in which heat is supplied at constant
volume and rejected at constant pressure is known
as
(a) Dual combustion cycle
(b) Diesel cycle
(c) Atkinson cycle
(d) Rankine cycle
(e) Stirling cycle.
Ans: c
146. The efficiency of Diesei cycle with decrease in
cut off
(a) increases
(b) decreases
(c) remains unaffected
(d) first increases and then decreases
(e) first decreases and then increases.
Ans: a
147. Which of the following cycles has maximum
efficiency
(a) Rankine
(b) Stirling
(c) Carnot
(d) Brayton
(e) Joule.
Ans: c
148. The ideal efficiency of a Brayton cycle without
regeneration with increase ni pressure ratio will
(a) increase
(b) decrease
(c) remain unchanged
(d) increase/decrease depending  on application
(e) unpredictable.
Ans: a
149. The ideal efficiency of a Brayton cycle with
regeneration, with increase in pressure ratio will
(a) increase
(b) decrease
(c) remain unchanged
(d) increase/decrease depending on ap-plication
(e) unpredictable. "
Ans: b
150. The following cycle is used for air craft
refrigeration
(a) Brayton cycle
(b) Joule cycle
(c) Carnot cycle
(d) Bell-Coleman cycle
(e) Reversed-Brayton cycle.
Ans: e
151. Gas turbine cycle consists of
(a) two isothermals and two isentropics
(b) two isentropics and two constant volumes
(c) two isentropics, one constant volume and one
constant pressure
(d) two isentropics and two constant pressures
(e) none of the above.
Ans: d
152. The thermodynamic difference between a
Rankine cycle working with saturated steam and the
Carnot cycle is that
(a) carnot cycle can't work with saturated steam
(b) heat is supplied to water at temperature below
the maximum temperature of the cycle
(c) a rankine cycle receives heat at two places
(d) rankine cycle is hypothetical
(e) none of the above.
Ans: b

Latest Machine Design Questions and Answers

Machine Design Questions and Answers

1. The ultimate strength of steel in tension in
comparison to shear is in the ratio of
(a) 1 : l
(b) 2:1
(c) 3 : 2
(d) 2 : 3
(e) 1 : 2
Ans: c
2. The permissible stress for carbon steel under
static loading is generally taken as
(a) 2000-3000 kg/pm2
(b) 3000-4000 kg/cm2
(c) 4000-4500 kg/cm2
(d) 7500-10,000 kg/cm2
(e) 10,000-15,000 kg/cm2.
Ans: c
3. The property of a material which enables it to
resist fracture due to high impact loads is known as
(a) elasticity
(b) endurance
(c) strength
(d) toughness
(e) resilience.
Ans: d
4. A hot short metal is
(a) brittle when cold
(b) brittle when hot
(c) brittle under all conditions
(d) ductile at high temperature
(e) hard when hot.
Ans: b
5. Guest's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: b
6. Rankine's theory of failure is applicable for
following type of materials
(a) brittle
(b) ductile
(c) elastic
(d) plastic
(e) tough.
Ans: a
7. If an unsupported uniform cross sectional elastic
bar is subjected to a longitudinal impact from a rigid
bob moving with velocity v, then a compressive
wave of intensity sc is propagated through the bar
as follows
(a) vpE
(b) vVvF
(c) WpE/2
(d) IvHpE
(e) none of the above, where E = modulus of
elasticity and p = mass density.
Ans: a
8. Tensile strength of a mild steel specimen can be
roughly predicted from following hardness test
(a) Brinell
(b) Rockwell
(c) Vicker
(d) Shore's sceleroscope
(e) none of the above.
Ans: a
9. Resilience of a material is important, when it is
subjected to
(a) combined loading
(b) fatigue
(c) thermal stresses
(d) wear and tear
(e) shock loading.
Ans: e
10. In the case of an elastic bar fixed at upper end
and loaded by a falling weight at lower end, the
shock load produced can be decreased by
(a) decreasing the cross-section area of' bar
(b) increasing the cross-section area of bar
(c) remain unaffected with cross-section area
(d) would depend upon other factors
(e) none of the above.
Ans: a
11. .Other method of reducing shock load in the
above case can be
(a) to decrease length
(b) to increase length
(c) unaffected by length
(d) other factors would decide same
(e) none of the above.
Ans: b
12. If a load W is applied instantaneously on a bar;
then the stress induced in bar will
(a) be independent of ratio of mass of load W to
mass of bar (y)
(b) increase with increase in y
(c) decrease with decrease in y
(d) depend on other considerations
(e) none of the above.
Ans: a
13. Brittle coating technique is used for
(a) determining brittleness
(b) protecting metal against corrosion
(c) protecting metal against wear and tear
(d) experimental stress analysis
(e) non-destructive testing of metals.
Ans: d
14. Stress concentration is caused due to
(a) variation in properties of material from point to
point in a member
(b) pitting at'points or areas at which loads on a
member are applied
(c) abrupt change of section
(d) all of the above
(e) none of the above.
Ans: d
15. The endurance limit of a material with finished
surface in comparison to rough surface is
(a) more
(b) less
(c) same
(d) more or less depending on quantum of load
(e) unpredictable.
Ans: a
16. Plastic flow in ductile materials
(a) increases the seriousness of static load-ing
stress concentration
(b) lessens the seriousness of static load¬ing
stress concentration
(c) has no effect on it
(d) depends on other considerations
(e) none of the above.
Ans: b
17. The maximum stress due to stress
concentration in a bar having circular transverse
hole, as compared to its static
stress without hole will be
(a) same in both cases
(b) 2 times more
(c) 3 times more
(d) 4 times more
(e) unpredictable.
Ans: c
18. The fatigue life of a part can be improved by
(a) electroplating
(b) polishing
(c) coating
(d) shot peening
(e) heat treating.
Ans: d
19. Stress concentration in static loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: b
20. Stress concentration in cyclic loading is more
serious in
(a) ductile materials
(b) brittle materials
(c) equally serious in both cases
(d) depends on other factors
(e) unpredictable.
Ans: a
21. Endurance limit or fatigue limit is the maximum
stress that a member can withstand for an infinite
number of load applications without failure when
subjected to
(a) dynamic loading
(b) static loading
(c) combined static and dynamic loading
(d) completely reversed loading
(e) all of the above.
Ans: d
22. Pick up wrong statement. Fatigue strength can
be increased by
(a) cold working
(b) shot peening
(c) grinding and lapping surface
(d) hot working
(e) using gradual changes of section.
Ans: d
23. Which of the following is not correct procedure
to increase the fatigue limit
(a) cold working
(b) shot peening
(c) surface decarburisation
(d) under-stressing
(e) all of the above.
Ans: c
24. Coaxing is the procedure of increasing
(a) metal strength by cycling
(b) metal hardness by surface treatment
(c) metal resistance to corrosion by coating
(d) fatigue limit by overstressing the metal by
successively increasing loadings
(e) none of the above.
Ans: d
25. Which is correct statement ?
Stress concentration in static loading is
(a) very serious in brittle materials and less serious
in ductile materials
(b) very serious in ductile materials and less
serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: a
26. The notch angle of the Izod impact test
specimen is
(a) 10°
(b) 20°
(c) 30°
(d) 45°
(e) 60°.
Ans: d
27. In Vicker's hardness testing, the pyramid
indentor apex is
(a) 40°
(b) 122°
(c) 136°
(d) 152°
(e) 161°.
Ans: c
28. Which is correct statement ?
Stress concentration in cyclic loading is
(a) very serious in brittle materials and less
serious in ductile materials
(b) very serious in ductile materials and less
serious in brittle materials
(c) equally serious in both types of materials
(d) seriousness would depend on other factors
(e) none of the above.
Ans: c
29. In testing a material for endurance strength, it is
subjected to
(a) static load
(b) dynamic load
(c) impact load
(d) static as well as dynamic load
(e) completely reversed load.
Ans: e
30. If a material fails below its yield point, failure
would be due to
(a) straining
(b) fatigue
(c) creep
(d) sudden loading
(e) impact loading.
Ans: b
31. The fatigue limit of a material
(a) is greatly decreased by poor surface conditions
(b) remains same irrespective of surface conditions
(c) depends mainly on core composition
(d) is dependent upon yield strength of material
(e) none of the above.
Ans: a
32. Cold working
(a) increases the fatigue strength
(b) decreases the fatigue strength
(c) has no influence on fatigue strength
(d) alone has no influence on fatigue strength
(e) none of the above.
Ans: a
33. Yield point in fatigue loading as compared to
static loading is
(a) same
(b) higher
(c) lower
(d) depends on other factors
(e) none of the above.
Ans: c
34. Residual stress in materials
(a) acts when external load is applied
(b) becomes zero when external load is removed
(c) is independent of external loads
(d) is always harmful
(e) is always beneficial.
Ans: c
35. The building up of worn and uridersized parts,
subjected to repeated loads by electroplating is
(a) best method
(b) extremely hazardous
(c) has no effect as regards fatigue strength
(d) cheapest method
(e) all of the above.
Ans: a
36. In nitrated parts, the origins of the fatigue
cracks will occur at
(a) surface
(b) just below the surface
(c) within the core
(d) could occur anywhere
(e) none of the above.
Ans: e
37. Which process will increase the fatigue duration
of parts ?
(a) finishing and polishing
(b) shot-peening
(c) decarburisation
(d) electroplating
(e) all of the above".
Ans: b
38. Which is correct statement ?
(a) a member made of steel will generally be more
rigid than a member of equal load-carrying ability
made of cast iron
(b) a member made of cast iron will generally be.
more rigid than a member of equal load carrying
ability made of steel
(c) both will be equally rigid
(d) which one is rigid will depend on several other
factors
(e) none of the above.
Ans: b
39. Resistance to fatigue of a material is measured
by
(a) Young's modulus
(b) coefficient of elasticity
(c) elastic limit
(d) ultimate tensile strength
(e) endurance limit.
Ans: e
40. In most machine members, the damping
capacity of the material should be
(a) low
(b) zero
(c) high
(d) could be anything
(e) none of the above.
Ans: c
41. The ratio of endurance limit in shear to the
endurance limit in flexure is
(a) 0.33
(b) 0.4
(c) 0.5
(d) 0.55
(e) 0.6
Ans: d
42. For steel, the ultimate strength in shear as
compared to ultimate strength in tension is
(a) same
(b) 1/2
(c) 1/3
(d) 1/4
(e) 2/3
Ans: e
43. The endurance limit in shear of carbon steel can
be obtained by multiplying the endurance limit in
flexure by a factor of
(a) 0.25
(b) 0.45
(r) 0.55
(d) 0.65
(e)0.75.
Ans: e
44. At low temperatures (say 75°C) the notched-bar
impact value of steel
(a) increases markedly
(b) decreases markedly
(c) remains same
(d) depends on heat treatment carried out
(e) none of the above.
Ans: b
45. A bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) is provided with pointed threads
(e) requires no nut.
Ans: a
46. The crest diameter of a screw thread is same
as
(a) major diameter
(b) minor diameter
(c) pitch diameter
(d) core diameter
(e) none of the above.
Ans: a
47. If d is the diameter of bolt hole then for a
flanged pipe joint to be leak proof, the
circumferential pitch of the bolts should be
(a) lOVZ
(b) 10VZtol5Vd
(c) 15Vdto20VZ
(d) 20Vdto30Vd
(e) 30V5"to40Vd.
Ans: d
48. Maximum principal stress theory is applicable
for
(a) ductile materials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: b
49. The following type of nut is used with alien bolt
(a) alien nut
(b) hexagonal nut
(c) slotted nut
(d) castle nut
(e) any one of the above.
Ans: e
50. A stud
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part to be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking nuts.
Ans: c
51. Shear stress theory is applicable for
(a) ductile fnaterials
(b) brittle materials
(c) elastic materials
(d) all of the above
(e) none of the above.
Ans: a
52. A tap bolt
(a) has a head on one end and a nut fitted to the
other
(b) has head at one end and other end fits into a
tapped hole in the other part \o be joined
(c) has both the ends threaded
(d) has pointed threads
(e) requires locking devices.
Ans: b
53. For applications involving high stresses in one
direction only the following type of thread would be
best suited
(a) ISO metric thread
(b) acme thread
(c) square thread
(d) buttress thread
(e) British Association thread.
Ans: d
54. The included angle in unified of American
National threads is
(a) 60°
(b) 55°
(c) 47°
(d) 29°
(e) none of the above.
Ans: a
55. The function of a washer is to
(a) provide cushioning effect
(b) provide bearing area
(c) absorb shocks and vibrations
(d) provide smooth surface in place of rough
surface
(e) act as a locking device.
Ans: b
56. Cap screws are
(a) similar to'small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween parts
(d) provided with detachable caps
(e) similar to stud.
Ans: a
57. An alien bolt is
(a) self locking bolt
(b) same as stud
(c) provided with hexagonal depression in head
(d) used in high speed components
(e) provided with countersunk head.
Ans: c
58. The deflection of a cantilever beam under load W
is 8. If its width is halved, then the deflection under
load W will be
(a) 28
(b) 8/2
(c) 48
(d) 8/4
(e) none of the above.
Ans: c
59. Ball bearing type screws are found in following
application
(a) screw jack
(b) aeroplane engines
(c) crane
(d) steering mechanism
(e) bench vice.
Ans: d
60. Set screws are
(a) similar to small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween parts
(d) similar to stud
(e) none of the above.
Ans: c
61. A self locking screw has
(a) fine threads
(b) coarse threads
(c) coefficient of friction > tangent of load angle
(d) hole for inserting split pin
(e) two nuts for locking.
Ans: c
62. The designation M 33 x 2 of a bolt means
(a) metric threads of 33 nos in 2 cm.
(b) metric threads with cross-section of 33 mm
(c) metric threads of 33 mm outside diameter and 2
mm pitch
(d) bolt of 33 mm nominal diameter having 2 threads
per cm
(e) none of the above.
Ans: c
63. Machine screws are
(a) similar to small size tap bolts except that a
greater variety of shapes of heads are available
(b) slotted for a screw driver and generally used
with a nut
(c) used to prevent relative motion be-tween two
parts
(d) similar to stud
(e) none of the above.
Ans: b
64. Rivets are generally specified by
(a) thickness of plates to be riveted
(b) length of rivet
(c) diameter of head
(d) nominal diameter
(e) all of the above.
Ans: d
65. The edges of a boiler plate are bevelled to an
angle of
(a) 30°
(b) 45°
(c) 60°
(d) 80°
(e) 85°.
Ans: d
66. Which of the following is a permanent
fastening ?
(a) bolts
(b) keys
(c) cotters
(d) rivets
(e) screws.
Ans: d
67. In order to avoid tearing of the plate at edge, the
distance from the center line of the rivet hole to the
nearest edge of the plate in terms of dia. of rivet d
should be equal to
(a) d
(b) 1.25 d
(c) 1.5 d
(d) 1.75 d
(e) 2 d.
Ans: c
68. If the tearing efficiency of a riveted joint is 75%,
then the ratio of diameter of rivet to the pitch is
equal to
(a) 0.2
(b) 0.25
(c) 0.50
(d) 0.6
(e) 0.75.
Ans: b
69. Transverse fillet welded joints are designed for
(a) tensile strength
(b) compressive strength
(c) shear strength
(d) bending strength
(e) torsional strength.
Ans: a
70. Jam nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening a screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter spitted and bent in reverse direction at other
end
(e) none of the above.
Ans: a
71. The pitch of threads on a Jock nut in
comparison to pitch of nut is
(a) same
(b) coarser
(c) finer
(d) very coarse
(e) very fine.
Ans: a
72.Buttress threads are usually found on
(a) screw cutting lathes
(b) feed mechanisms
(c) spindles of bench vices
(d) screw jack
(e) railway carriage couplings.
Ans: e
73. In order to obtain bolt of uniform strength
(a) increase shank diameter
(b) increase its length
(c) drill an axial hole through head up to threaded
portion so that shank area is equal to root area of
thread
(d) tighten die bolt properly
(e) all of the above.
Ans: c
74. A key capable of tilting in a recess milled out in
a shaft is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
75. A key made from a cylindrical disc having
segmental cross-section, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: a
76. A tapered key which fits in a keyway in the hub
and is flat on the shaft, is known as
(a) wood-ruff key
(b) feather key
(c) flat saddle key
(d) gib head key
(e) hollow saddle key.
Ans: c
77. Fibrous fracture occurs in
(a) ductile material
(b) brittle material
(c) elastic material
(d) hard material
(e) all of the above.
Ans: a
78. Turn buckle has
(a) right hand threads on bout ends
(b) left hand threads on both ends
(c) left hand threads on one end and right hand
threads on other end
(d) no threads
(e) threads in middle portion.
Ans: c
79. Eye bolts are used for
(a) foundation purposes
(b) locking devices *
(c) absorbing shock and vibrations
(d) transmission of power
(e) lifting and transportation of machines and
cubicles.
Ans: e
80. Elastic nut is a locking device in which
(a) one small nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening a screw
(c) hard fiber or nylon cotter is recessed in the nut
and becomes threaded as the nut is stewed on the
bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter pin splitted and bent in reverse direction at
other end
(e) none of the above,
Ans: c
81. If d is the normal diameter of a bolt in mm, then
the initial tension in kg in a bolt used for making a
fluid tight joint as for steam engine cover joint is
calculated by the relation
(a) 102 d
(b) 124 d
(c) 138 d
(d) 151 d
(e) 168 d.
Ans: e
82. If threads on a bolt are left hand, threads on nut
will be
(a) right hand with same pitch
(b) left hand with same pitch
(c) could be left or right hand
(d) right hand with fine pitch
(e) left hand with fine pitch.
Ans: b
83. Taper usually provided on cotter is
(a) 1 in 5
(b) 1 in 10
(c) 1 in 24
(d) 1 in 40
(e) 1 in 50.
Ans: c
84. Applications in which stresses are encountered
in one direction only uses following type of threads
(a) metric
(b) buttress
(c) acme
(d) square
(e) BSW.
Ans: b
85. The draw of cotter need not exceed
(a) 3 mm
(b) 5 mm
(c) 10 mm
(d) 20 mm
(e) 25 mm.
Ans: a
86. A bench vice has following type of threads
(a) metric
(b) square
(c) buttress
(d) acme
(e) BSW.
Ans: d
87. The valve rod in a steam engine is connected to
an eccentric rod by
(a) cotter joint
(b) bolted joint
(c) kunckle joint
(d) universal coupling
(e) gib and cotter joint.
Ans: c
88. Split nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly in middle of nut and then slot
reduced by tightening screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter-pin is
passed through these and a hole in the bolt, and
cotter pin splitted and bent in reverse direction at
the other end
(e) none of the above.
Ans: b
89. Taper on the cotter and slot is provided
(a) on both the sides
(b) on one side only
(c) on none of the sides
(d) may be provided anywhere
(e) none of the above.
Ans: b
90. The function of cutting oil when threading a pipe
is to
(a) provide cooling action
(b) lubricate the dies
(c) help remove chips
(d) all of the above
(e) none of the above.
Ans: d
91. Silver-based solder is used for
(a) flaring
(b) brazing
(c) soft soldering
(d) fusion welding
(e) none of the above.'
Ans: b
92. For tight leakage joints, following type of thread
is best suited
(a) metric
(b) buttress
(c) square
(d) acme
(e) NPT (national pipe threads).
Ans: e
93. In order to permit the thermal expansion/
contraction of tubing, it should be
(a) crimped
(b) honed
(c) flared
(d) bent
(e) none of the above.
Ans: d
94. A tube has the following advantage over pipe
(a) lighter and easier to handle
(b) greater shock absorption
(c) smoother inside walls
(d) all of the above
(e) none of the above.
Ans: d
95. The strap end of a connecting rod of steam
engine is joined by
(a) gib of cotter joint
(b) sleeve and cotter joint
(c) spigot socket cotter joint
(d) knuckle joint
(e) universal coupling.
Ans: a
96. A backing ring is used inside the pipe joint when
making a
(a) butt weld
(b) fillet weld
(c) sleeve weld
(d) socket weld
(e) tube weld.
Ans: a
97. The shear plane in case of bolts should
(a) be across threaded portion of shank
(b) be parallel to axis of bolt
(c) be normal to threaded portion of shank
(d) never be across the threaded portion
(e) none of the above.
Ans: d
97. Castle nut is a locking device in which
(a) one smaller nut is tightened over main nut and
main nut tightened against smaller one by
loosening, creating friction jamming
(b) a slot is cut partly is middle of nut and then slot
reduced by tightening a screw
(c) a hard fiber or nylon cotter is recessed in the
nut and becomes threaded as the nut is screwed on
the bolt causing a tight grip
(d) through slots are made at top and a cotter pin is
passed through these and a hole in the bolt, and
cotter pin spitted and bent in reverse direction at
other end
(e) none of the above.
Ans: d
98. When a nut is tightened by plaping a washer
below it, the bolt will be subjected to following type
of loads
(a) compression
(b) tension
(c) shear
(d) combined loads
(e) all of the above.
Ans: b
99. Gear box is used
(a) to produce torque
(b) for speed reduction
(c) to obtain variable speeds
(d) to increase efficiency of system
(e) to damp out vibrations.
Ans: c
100. The edges of the plates for cylindrical vessels
are usually bevelled to an angle of 80° for
(a) reducing stress concentration
(b) ease of manufacture
(c) safety
(d) fullering and caulking
(e) all of the above.
Ans: d
101. The piston rod of a steam engine is usually
connected to the crosshead by means of
(a) bolted joint
(b) kunckle joint
(c) cotter joint
(d) universal joint
(e) universal coupling.
Ans: c
102. Which of the following pipe joints would be
suitable for pipes carrying steam
(a) flanged
(b) threaded
(c) bell and spigot
(d) expansion
(e) compression.
Ans: d
103. Spring index is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) indication of quality of spring
(e) nothing.
Ans: a
104. The shearing stresses in the inner face as
compared to outer face of the wire in a heavy close
coiled spring is
(a) larger
(b) smaller
(c) equal
(d) larger/smaller depending on diameter of spring
coil
(e) unpredictable.
Ans: a
105. Form coefficient of spring is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) concerned With strength of wire of spring
(e) nothing
Ans: c
106. Spring stiffness is
(a) ratio of coil diameter to wire diameter
(b) load required to produce unit deflection
(c) its capability of storing energy
(d) its ability to absorb shocks
(e) none of the above.
Ans: b
107. When two springs are in series (having
stiffness K), the equivalent stiffness will be
(a) K
(b) K/2
(c) 2K
(d) KIA
(e) UK.
Ans: b
108. When a close coiled helical spring is
compressed, its wire is subjected to
(a) tension
(b) shear
(c) compression
(d) all of the above
(e) none of the above.
Ans: a
109. If a spring is cut down into two springs, the
stiffness of cut springs will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
110. Belt slip may occur due to
(a) heavy load
(b) loose belt
(c) driving pulley too small
(d) all of the above
(e) none of the above.
Ans: d
111. Aircraft body is usually fabricated by
(a) welding
(b) precasting
(c) rivetting
(d) casting
(e) unconventional methods.
Ans: c
112. If two springs are in parallel then their overall
stiffness will be
(a) half
(b) same
(c) double
(d) unpredictable
(e) none of the above.
Ans: c
113. In hydrodynamic bearings
(a) the oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease is used for lubrication
(e) none of the above.
Ans: a
114. Antifriction bearings are
(a) sleeve bearings
(b) hydrodynamic bearings
(c) thin lubricated bearings
(d) ball and roller bearings
(e) none of the above.
Ans: e
115. If p = bearing pressure on projected bearing
area, z = absolute viscosity of lubricant, and N =
speed of journal, then the bearing characteristic
number is given by
(a) ZN/p
(b) p/ZN
(c) Z/pN
(d) N/Zp
(e) Zp/N.
Ans: a
116. The usual clearance provided in hydrodynamic
bearing per mm of diameter of shaft is
(a) 0.01 micron
(b) 0.1 micron
(c) 1 micron
(d) 10 microns
(e) 25 microns.
Ans: c
117. In hydrostatic bearings
(a) the Oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease is used for lubrication
(e) none of the above.
Ans: b
118. Oil in journal bearing should be applied at the
point where load is
(a) nil or lightest
(b) maximum
(c) average
(d) any one of the above
(e) unpredictable.
Ans: a
119. The rated life of a bearing varies
(a) directly as load
(b) inversely as square of load
(c) inversely as cube of load
(d) inversely as fourth power of load
(e) none of the above.
Ans: c
120. In oilness bearings
(a) the oil film pressure is generated only by the
rotation of the journal
(b) the oil film is maintained by supplying oil under
pressure
(c) do not require external supply of lubricant
(d) grease required to be applied after some
intervals
(e) none of the above.
Ans: c
121. In V-belt drive, belt touches
(a) at bottom
(b) at sides only
(c) both at bottom and sides
(d) could touch anywhere
(e) none of the above.
Ans: b
122. Three different weights fall from a certain
height under vacuum. They will take
(a) same time to reach earth
(b) times proportional to weight to reach earth
(c) times inversely proportional to weight to reach
earth
(d) unpredictable
(e) none of the above.
Ans: a
123. In cross or regular lay ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: a
124. In standard taper roller bearings, the angle of
taper of outer raceway is
(a) 5°
(b) 8°
(c) 15°
(d) 25°
(e) 40°.
Ans: d
125. In composite or reverse laid ropes
(a) direction of twist of wires in strands is opposite
to the direction of twist of strands
(b) direction of twist of wires and strands are same
(c) wires in two adjacent strands are twisted in
opposite direction
(d) wires are not twisted
(e) none of the above.
Ans: c
126. Whether any core is required in wire ropes
(a) yes
(b) no
(c) sometimes
(d) rarely
(e) very often.
Ans: a
127. If shearing stress in nut is half the tensile
stress in a bolt, then nut length should be equal to
(a) diameter of bolt
(b) 0.75 x diameter of bolt
(c) 1.25 x diameter of bolt
(d) 1.5 x diameter of bolt
(e) 0.5 x diameter of bolt.
Ans: a
128. Basic shaft is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: a
129. Basic hole is one
(a) whose upper deviation is zero
(b) whose lower deviation is zero
(c) whose lower as well as upper deviations are
zero
(d) does not exist
(e) none of the above.
Ans: b
130. I.S. specifies following total number of grades
of tolerances
(a) 18
(b) 16
(c) 20
(d) 22
(e) 14.
Ans: a
131. For standard coarse threads of nut, the threads
will be as strong in failure by shear as the bolt in
tension, if the height of nut (h) is approximately
(a) 0.4 times
(b) 0.6 times
(c) 0.7 times
(d) 0.8 times
(e) 0.9 times the normal diameter of bolt.
Ans: a
132. Allen bolts are
(a) self locking bolts
(b) designed for shock load
(c) used in aircraft application
(d) provided with hexagonal depression in head
(e) uniform strength bolts.
Ans: d
133. The resultant axial load on a bolt depends on
(a) initial tension
(b) external load applied
(c) relative elastic yielding (springness) of the bolt
and the connected member
(d) (a) and (b) above
(e) (a), (b) and (c) above.
Ans: e
134. The connecting rod bolts are tightened up so
that tightening stress
(a) is just sufficient to hold parts together
(b) approaches yield point
(c) is 50% of yield point
(d) is about yield point divided by safety factor
(e) none of the above.
Ans: b
135. The connecting rod bolts are tightened up with
initial tension greater than the external load so that
(a) joint may not open up
(b) bolts are weakest elements
(c) the resultant load on the bolt would not be
affected by the external cyclic load
(d) bolts will not loosen during service
(e) none of the above.
Ans: c
136. If an application calls for stresses on screw
threads in one direction only, then the following type
of thread would be best suited
(a) square
(b) acme
(c) buttress
(d) BSW
(e) metric.
Ans: c
137. When a bolt is subjected to shock loading, the
resilience of the bolt should be considered in order
to prevent breakage at
(a) shank
(b) head
(c) in the middle
(d) at the thread
(e) anywhere in the bolt.
Ans: d
138. The shock absorbing capacity of a bolt can be
increased by
(a) tightening it properly
(b) increasing shank diameter
(c) grinding the shank
(d) using washer
(e) making shank diameter equal to core diameter
of thread.
Ans: e

136 TOP Engineering Mechanics - Mechanical Engineering Multiple choice Questions and Answers Latest Engineering Mechanics Questions and Answers List

Engineering Mechanics Objective type Questions and Answers

1. The unit of force in S.I. units is
(a) kilogram
(b) newton
(c) watt
(d) dyne
(e) joule.
Ans: b
2. The unit of work or energy in S.I. units is
(a) newton
(b) pascal
(c) kilogram meter
(d) watt
(e) joule.
Ans: e
3. The unit of power in S.I. units is
(a) newton meter
(b) watt
(c) joule
(d) kilogram meter/sec.
(e) pascal per sec.
Ans: b
4. Forces are called concurrent when their lines of
action meet in
(a) one point
(b) two points
(c) plane
(d) perpendicular planes
(e) different planes.
Ans: a
5. Forces are called coplanar when all of them
acting on body lie in
(a) one point
(b) one plane
(c) different planes
(d) perpendicular planes
(e) different points.
Ans: b
6. A force acting on a body may
(a) introduce internal stresses
(b) balance the other forces acting on it
(c) retard its motion
(d) change its motion
(e) all of the above.
Ans: e
7. Which is the correct statement about law of
polygon of forces ?
(a) if any number of forces acting at a point can be
represented by the sides
of a polygon taken in order, then the forces are in
equilibrium
(b) if any number of forces acting at a point can be
represented in direction and magnitude by the sides
of a polygon, then the forces are in equilibrium
(c) if a polygon representing forces acting at a point
is closed then forces are in equilibrium
(d) if any number of forces acting at a point can be
represented in direction and magnitude by the sides
of a polygon taken in order, then the forces are in
equilibrium
(e) none of the above.
Ans: d
8. Effect of a force on a body depends upon
(a) magnitude
(b) direction
(c) positionor line of action
(d) all of the above
(e) none of the above.
Ans: d
9. If a number of forces act simultaneously on
a particle, it is possible
(a) not a replace them by a single force
(b) to replace them by a single force
(c) to replace them by a single force through C.G.
(d) to replace them by a couple
(e) to replace them by a couple and a force.
Ans: b
11. A force is completely defined when we specify
(a) magnitude
(b) direction
(c) point of application
(d) all of the above
(e) none of the above.
Ans: d
12. If two equal forces of magnitude P act at an
angle 9°, their resultant will be
(a) P/2 cos 9/2
(b) IP sin 9/2
(c) 2P tan 9/2
(d) IP cos 9/2
(e) Psin 9/2.
Ans: d
13. The algebraic sum of the resolved parts of a
number of forces in a given direction is equal to the
resolved part of their resultant in the same
direction. This is as per the principle of
(a) forces
(b) independence of forces
(c) dependence of forces
(d) balance of force
(e) resolution of forces.
Ans: e
14. The resolved part of the resultant of two forces
inclined at an angle 9 in a given direction is equal to
(a) the algebraic sum of the resolved parts of the
forces in the given direction
(b) the sum of the resolved parts of the forces in
the given direction
(c) the difference of the forces multiplied by the
cosine of 9
(d) the sum of the forces multiplied by the sine of 9
(e) the sum of the forces multiplied by the tangent of
9.
Ans: a
15. Which of the following do not have identical
dimensions ?
(a) Momentum and impulse
(b) Torque and energy
(c) Torque and work
(d) Kinetic energy and potential energy
(e) Moment of a force and angular momentum.
Ans: e
16. Which of the following is not the unit of
distance ?
(a) angstrom
(b) light year
(c) micron
(d) millimetre
(e) milestone.
Ans: e
17. Which of the following is not the unit of power ?
(a) kW (kilowatt)
(b) hp (horse power)
(c) kcal/sec
(d) kg m/sec
(e) kcal/kg sec.
Ans: e
18. Which of the following is not the unit of work,
energy and heat ?
(a) kcal
(b) kg m
(c) kWhr
(d) hp
(e) hp hr.
Ans: d
19. Which of the following is not the unit of
pressure ?
(a) kg/cm
(b) ata
(c) atmosphere
(d) mm of wcl
(e) newton.
Ans: e
20. The weight of a body is due to
(a) centripetal force of earth
(b) gravitational pull exerted by the earth
(c) forces experienced by body in atmosphere
(d) force of attraction experienced by particles
(e) gravitational force of attraction towards the
center of the earth.
Ans: e
21. The forces, which meet at one point, but their
lines of action do not lie in a plane, are called
(a) coplanar non-concurrent forces
(b) non-coplanar concurrent forces
(c) non-coplanar non-concurrent forces
(d) intersecting forces
(e) none of the above.
Ans: b
22. When trying to turn a key into a lock, following is
applied
(a) coplanar force
(b) non-coplanar forces
(c) lever
(d) moment
(e) couple.
Ans: e
23. Which of the following is not a scalar quantity
(a) time
(b) mass
(c) volume
(d) density
(e) acceleration.
Ans: e
24. According to principle of transmissibility of
forces, the effect of a force upon a body is
(a) maximum when it acts at the center of gravity of
a body
(b) different at different points in its line of action
(c) the same at every point in its line of action
(d) minimum when it acts at the C.G. of the body
(e) none of the above.
Ans: c
25. Which of the following is a vector quantity
(a) energy
(b) mass
(c) momentum
(d) angle
(e) speed.
Ans: c
26. The magnitude of two forces, which when acting
at right angle produce resultant force of VlOkg and
when acting at 60° produce resultant of Vl3 kg.
These forces are
(a) 2 and V6
(b) 3 and 1 kg
(c) V5andV5
(d) 2 and 5
(e) none of the above.
Ans: c
27. A number of forces acting at a point will be in
equilibrium if
(a) their total sum is zero
(b) two resolved parts in two directions at right
angles are equal
(c) sum of resolved parts in any two per-pendicular
directions are both zero
(d) all of them are inclined equally
(e) none of the above.
Ans: c
28. Two non-collinear parallel equal forces acting in
opposite direction
(a) balance each other
(b) constitute a moment
(c) constitute a couple
(d) constitute a moment of couple
(e) constitute a resultant couple.
Ans: c
29. According to principle of moments
(a) if a system of coplanar forces is in equilibrium,
then their algebraic sum is zero
(b) if a system of coplanar forces is in equilibrium,
then the algebraic sum of their moments about any
point in their plane is zero
(c) the algebraic sum of the moments of any two
forces about any point is equal to moment of
theiwesultant about the same point
(d) positive and negative couples can be balanced
(e) none of the above.
Ans: b
30. Which of the following is not a vector quantity
(a) weight
(b) velocity
(c) acceleration
(d) force
(e) moment.
Ans: a
31. According to law of triangle of forces
(a) three forces acting at a point will be in
equilibrium
(b) three forces acting at a point can be represented
by a triangle, each side being proportional to force
(c) if three forces acting upon a patticle are
represented in magnitude and direction by the sides
of a triangle, taken in order, they will be in
equilibrium
(d) if three forces acting at a point are in
equilibrium, each force is proportional to the sine of
the angle between the other two
(e) none of the above.
Ans: c
33. If a rigid body is in equilibrium under the action
of three forces, then
(a) these forces are equal
(b) the lines of action of these forces meet in a point
(c) the lines of action of these forces are parallel
(d) (b) and (c) above
(e) none of the above.
Ans: d
34. D' Alembert's principle is used for
(a) reducing the problem of kinetics to equivalent
statics problem
(b) determining stresses in the truss
(c) stability of floating bodies
(d) designing safe structures
(e) solving kinematic problems.
Ans: a
35. A heavy ladder resting on floor and against a
vertical wall may not be in equilibrium, if
(a) the floor is smooth, the wall is rough
(b) the floor is rough, the wall is smooth
(c) the floor and wall both are smooth surfaces
(d) the floor and wall both are rough surfaces
(e) will be in equilibrium under all conditions.
Ans: c
38. According to Lami's theorem
(a) three forces acting at a point will be in
equilibrium
(b) three forces acting at a point can be represented
by a triangle, each side being proportional to force
(c) if three forces acting upon a particle are
represented in magnitude and
direction by the sides of a triangle, taken in order,
they will be in equilibrium
(d) if three forces acting at a point are in
equilibrium, each force is proportional to the sine of
the angle between the other two
(e) none of the above.
Ans: d
39. Two coplanar couples having equal and opposite
moments
(a) balance each other
(b) produce a couple and an unbalanced force
(c) are equivalent
(d) produce a moment of couple
(e) can not balance each other.
Ans: e
40. A framed structure is perfect if it contains
members equal to
(a) 2n-3
(b) n-l
(c) '2n-l
(d) n - 2
(e) 3n-2.
where n = number of joints in a frame
Ans: a
42. The product of either force of couple with the
arm of the couple is called
(a) resultant couple
(b) moment of the forces
(c) resulting couple
(d) moment of the couple
(e) none of the above.
Ans: d
43. In detennining stresses in frames by methods of
sections, the frame is divided into two parts by an
imaginary section drawn in such a way as not to cut
more than
(a) two members with unknown forces of the frame
(b) three members with unknown forces of the
frame
(c) four members with unknown forces of the frame
(d) three members with known forces of the frame
(e) four members with two known forces.
Ans: b
44. The center of gravity of a uniform lamina lies at
(a) the center of heavy portion
(b) the bottom surface
(c) the mid point of its axis
(d) all of the above
(e) none of the above.
Ans: c
45. Center of gravity of a solid cone lies on the axis
at the height
(a) one-fourth of the total height above base
(b) one-third of the total height above base
(c) one-half of the total height above base
(d) three-eighth of the total height above the base
(e) none of the above.
Ans: a
46. Center of percussion is
(a) the point of C.G.
(b) the point of metacentre
(c) the point of application of the resultant of all the
forces tending to cause a body to rotate about a
certain axis
(d) point of suspension
(e) the point in a body about which it can rotate
horizontally and oscillate under the influence of
gravity.
Ans: c
47. Center of gravity of a thin hollow cone lies on
the axis at a height of
(a) one-fourth of the total height above base
(b) one-third of the total height above base
(c) one-half of the total height above base
(d) three-eighth of the total height above the base
(e) none of the above.
Ans: b
48. The units of moment of inertia of an area are
(a) kg m2
(b) m4
(c) kg/m2
(d) m3
(e) kg/m4.
Ans: b
49. The center of percussion of the homogeneous
rod of length L suspended at the top will be
(a) L/2
(b) L/3
(c) 3L/4
(d) 2L/3
(e) 3L/8.
Ans: d
50. The center of gravity of a triangle lies at the
point of
(a) concurrence of the medians
(b) intersection of its altitudes
(c) intersection of bisector of angles
(d) intersection of diagonals
(e) all of the above.
Ans: a
51. The units of moment of inertia of mass are
(a) kg m2
(b) m4
(c) kg/m2
(d) kg/m
(e) m2/kg.
Ans: a
52. The possible loading in various members of
framed structures are
(a) compression or tension
(b) buckling or shear
(c) shear or tension
(d) all of the above
(e) bending.
Ans: a
53. A heavy string attached at two ends at same
horizontal level and when central dip is very small
approaches the following curve
(a) catenary
(b) parabola
(c) hyperbola
(d) elliptical
(e) circular arc.
Ans: b
54. A trolley wire weighs 1.2 kg per meter length.
The ends of the wire are attached to two poles 20
meters apart. If the horizontal tension is 1500 kg
find the dip in the middle of the span
(a) 2.5 cm
(b) 3.0 cm
(c) 4.0 cm
(d) 5.0 cm
(e) 2.0 cm.
Ans: c
55. From a circular plate of diameter 6 cm is cut out
a circle whose diameter is a radius of the plate.
Find the e.g. of the remainder from the center of
circular plate
(a) 0.5 cm
(b) 1.0 cm
(c) 1.5 cm
(d) 2.5 cm
(e) 0.25 cm.
Ans: a
58. Pick up the incorrect statement from the
following :
(a) The C.G. of a circle is at its center
(b) The C.G. of a triangle is at the intersection of
its medians
(c) The C.G. of a rectangle is at the inter-section of
its diagonals
(d) The C.G. of a semicircle is at a distance of r/2
from the center
(e) The C-G. of an ellipse is at its center.
Ans: d
59. The center of percussion of a solid cylinder of
radius r resting on a horizontal plane will be
(a) r/2
(b) 2r/3
(c) r/A
(d) 3r/2
(e) 3r/A.
Ans: d
62. In the equation of virtual work, following force is
neglected
(a) reaction of any smooth surface with which the
body is in contact
(b) reaction of a rough surface of a body which rolls
on it without slipping
(c) reaction at a point or an axis, fixed in space,
around which a body is con-strained to turn
(d) all of the above
(e) none of the above.
Ans: d
63. If a suspended body is struck at the center of
percussion, then the pressure on die axis passing
through the point of suspension will be
(a) maximum
(b) minimum
(c) zero
(d) infinity
(e) same as the force applied.
Ans: c
65. The resultant of the following three couples 20
kg force, 0.5 m arm, $ ve sense 30 kg force, 1 m
arm, - ve sense 40 kg force, 0.25 m arm, + ve
sense having arm of 0.5 m will be
(a) 20 kg, - ve sense
(b) 20 kg, + ve sense
(c) 10 kg, + ve sense
(d) 10 kg, - ve sense
(e) 45 kg, + ve sense.
Ans: a
68. Angle of friction is the
(a) angle between normal reaction and the
resultant of normal reaction and the limiting friction
(b) ratio of limiting friction and normal reaction
(c) the ratio of minimum friction force to the
friction force acting when the body is just about to
move
(d) the ratio of minimum friction force to friction
force acting when the body is in motion
(e) ratio of static and dynamic friction.
Ans: a
69. The coefficient of friction depends on
(a) area of contact
(b) shape of surfaces
(c) strength of surfaces
(d) nature of surface
(e) all of the above.
Ans: d
70. Least force required to draw a body up the
inclined plane is W sin (plane inclination + friction
angle) applied in the direction
(a) along the plane
(b) horizontally
(c) vertically
(d) at an angle equal to the angle of friction to the
inclined plane
(e) unpredictable.
Ans: d
71. The ratio of limiting friction and normal reaction
is known as
(a) coefficient of friction
(b) angle of friction
(c) angle of repose
(d) sliding friction
(e) friction resistance.
Ans: a
72. Which one of the following statements is not
correct
(a) the tangent of the angle of friction is equal to
coefficient of friction
(b) the angle of repose is equal to angle of friction
(c) the tangent of the angle of repose is equal to
coefficient of friction
(d) the sine of the angle of repose is equal to
coefficient to friction
(e) none of the above.
Ans: d
73. On a ladder resting on smooth ground and
leaning against vertical wall, the force of friction will
be
(a) towards the wall at its upper end
(b) away from the wall at its upper end
(c) upwards at its upper end
(d) downwards at its upper end
(e) none of the above.
Ans: c
74. On the ladder resting on the ground and leaning
against a smooth vertical wall, the force of friction
will be
(a) downwards at its upper end
(b) upwards at its upper end
(c) perpendicular to the wall at its upper end
(d) zero at its upper end
(e) none of the above.
Ans: d
76. Frictional force encountered after
commencement of motion is called
(a) post friction
(b) limiting friction
(c)  kinematic friction
(d) frictional resistance
(e) dynamic friction.
Ans: e
77. Coefficient of friction is the
(a) angle between normal reaction and the resultant
of normal reaction and the limiting friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just
about to move
(d) the friction force acting when the body is in
motion
(e) tangent of angle of repose.
Ans: b
78. Pick up wrong statement about friction force for
dry surfaces. Friction force is
(a) proportional to normal load between the
surfaces
(b) dependent on the materials of contact surface
(c) proportional to velocity of sliding
(d) independent of the area of contact surfaces
(e) none of the above is wrong statement.
Ans: c
79. A body of weight W on inclined plane of a being
pulled up by a horizontal force P will be on the point
of motion up the plane when P is equal to
(a) W
(b) W sin (a + $)
(c) Wtan(a + <|))
(d) W\an(a-<t>)
(e) Wtana.
Ans: c
80. A particle moves along a straight line such that
distance (x) traversed in t seconds is given by x =
t2 (t - 4), the acceleration of the particle will be
given by the equation
(a) 3t2-lt
(b) 3t2+2t
(c) 6f-8
(d) 6f-4
(e) 6t2-8t.
Ans: c
81. If rain is falling in the opposite direction of the
movement of a pedestrain, he has to hold his
umbrella
(a) more inclined when moving
(b) less inclined when moving
(c) more inclined when standing
(d) less inclined when standing
(e) none of the above.
Ans: d
86. A projectile is fired at an angle 9 to the vertical.
Its horizontal range will be maximum when 9 is
(a) 0°
(b) 30°
(c) 45°
(d) 60°
(e) 90°.
Ans: c
88. Limiting force of friction is the
(a) tangent of angle between normal-reaction and
the resultant of normal reaction and limiting friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just
about to move
(d) the friction force acting when the body is in
motion
(e) minimum force of friction.
Ans: c
89. Coulomb friction is the friction between
(a) bodies having relative motion
(b) two dry surfaces
(c) two lubricated surfaces
(d) solids and liquids
(e) electrically charged particles.
Ans: a
90. Dynamic friction as compared to static friction
is
(a) same
(b) more
(c) less
(d) may be less of more depending on nature of
surfaces and velocity
(e) has no correlation.
Ans: c
92. Tangent of angle of friction is equal to
(a) kinetic friction
(b) limiting friction
(c) angle of repose
(d) coefficient of friction
(e) friction force.
Ans: d
93. Kinetic friction is the
(a) tangent of angle between normal reaction and
the resultant of normal reaction and the limiting
friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just
about to move
(d) the friction force acting when the body is in
motion
(e) dynamic friction.
Ans: d
95. The effort required to lift a load W on a screw
jack with helix angle a and angle of friction <j) is
equal to
(a) Wtan(a + <)>)
(b) Wtan(a-<)>)
(c) Wcos(a + <t>)
(d) Wsin(a + <(>)
(e) W (sin a + cos <j>).
Ans: a
96. A semi-circular disc rests on a horizontal
surface with its top flat surface horizontal and
circular portion touching down. The coefficient of
friction between semi-cricular disc and horizontal
surface is \i. This disc is to be pulled by a horizontal
force applied at one edge and it always remains
horizontal. When the disc is about to start moving,
its top horizontal force will
(a) remain horizontal
(b) slant up towards direction of pull
(c) slant down towards direction of pull
(d) unpredictable
(e) none of the above.
Ans: c
97. A particle inside a hollow sphere of radius r,
having coefficient of friction -rr can rest upto height
of
(a) r/2
(b) r/A
(c) r/%
(d) 0.134 r
(e) 3r/8.
Ans: d
98. The algebraic sum of moments of the forces
forming couple about any point in their plane is
(a) equal to the moment of the couple
(b) constant
(c) both of above are correct
(d) both of above are wrong
(e) none of the above.
Ans: a
99. A single force and a couple acting in the
same plane upon a rigid body
(a) balance each other
(b) cannot balance each other
(c) produce moment of a couple
(d) are equivalent
(e) none of the above.
Ans: b
100. If three forces acting in one plane upon a rigid
body, keep it in equilibrium, then they must either
(a) meet in a point
(b) be all parallel
(c) at least two of them must meet
(d) all the above are correct
(e) none of the above.
Ans: d
101. The maximum frictional force which comes
into play when a body just begins to slide over
another surface is called
(a) limiting friction
(b) sliding friction
(c) rolling friction
(d) kinematic friction
(e) dynamic friction.
Ans: a
102. The co-efficient of friction depends upon
(a) nature of surfaces
(b), area of contact
(c) shape of the surfaces
(d) ail of the above.
(e) (a) and (b) above.
Ans: a
104. The necessary condition for forces to be in
equilibrium is that these should be
(a) coplanar
(b) meet at one point ;
(c) both (a) and (b) above
(d) all be equal
(e) something else.
Ans: c
105. If three forces acting in different planes can be
represented by a triangle, these will be in
(a) non-equilibrium
(b) partial equilibrium
(c) full equilibrium
(d) unpredictable
(e) none of the above.
Ans: a
106. If n = number of members andy = number of
joints, then for a perfect frame, n =
(a) j-2
(b) 2j-l
(c) 2/-3
(d) 3/-2
(e) 2/ -4.
Ans: c
107. A body moves, from rest with a constant
acceleration of 5 m per sec. The distance covered
in 5 sec is most nearly
(a) 38 m
(b) 62.5 m
(C) 96 m
(d) 124 m
(e) 240 m.
Ans: b
108. A flywheel on a motor goes from rest to 1000
rpm in 6 sec. The number of revolutions made is
nearly equal to
(a) 25
(b) 50
(c) 100
(d) 250
(e) 500.
Ans: b
109. Which of the following is the locus of a point
that moves in such a manner that its distance from
a fixed point is equal to its distance from a fixed line
multiplied by a constant greater than one
(a) ellipse
(b) hyperbola
(c) parabola
(d) circle
(e) none of the above.
Ans: b
111. Which of the following is not the unit of energy
(a) kg m
(b) kcal
(c) wattr
(d) watt hours
(e) kg m x (m/sec)2.
Ans: c
112. A sample of metal weighs 219 gms in air, 180
gms in water, 120 gms in an unknown fluid. Then
which is correct statement about density of metal
(a) density of metal can't be determined
(b) metal is twice as dense as water
(c) metal will float in water
(d) metal is twice as dense as unknown fluid
(e) none of the above.
Ans: a
113. The C.G. of a solid hemisphere lies on the
central radius 3r
(a) at distance — from the plane base 3r
(b) at distance — from the plane base 3r
(c) at distance — from the plane base 3r
(d) at distance — from the plane base or
(e) at distance — from the plane base.
Ans: d
117. The C.G. of a plane lamina will not be at its
geometrical centre in the case of a
(a) right angled triangle
(b) equilateral triangle
(c) square
(d) circle
(e) rectangle.
Ans: a
119. The C.G. of a right circular solid cone of height
h lies at the following distance from the base
(a) h/2
(b) J/3
(c) h/6
(d) h/4
(e) 3/i/5.
Ans: d
122. The M.I. of hollow circular section about a
central axis perpendicular to section as compared
to its M.I. about horizontal axis is
(a) same
(b) double
(c) half
(d) four times
(e) one fourth.
Ans: b
126. Which of the following is the example of lever
of first order
(a) arm of man
(b) pair of scissors
(c) pair of clinical tongs
(d) all of the above
(e) none of the above.
Ans: d
127. A pair of smith's tongs is an example of the
lever of
(a) zeioth order
(b) first order
(c) second order
(d) third order
(e) fourth order.
Ans: c
128. In the lever of third order, load W, effort P and
fulcrum F are oriented as follows
(a) W between P and F
(b) F between W and P
(c) P between W and F
(d) W, P and F all on one side
(e) none of the above.
Ans: a
129. The angle which an inclined plane makes with
the horizontal when a body placed on it is about to
move down is known as angle of
(a) friction
(b) limiting friction
(c) repose
(d) kinematic friction
(e) static friction.
Ans: c
130. In actual machines
(a) mechanical advantage is greater than velocity
ratio
(b) mechanical advantage is equal to velocity ratio
(c) mechanical advantage is less than velocity ratio
(d) mechanical advantage is unity
(e) none of the above.
Ans: c
131. In ideal machines
(a) mechanical advantage is greater than velocity
ratio
(b) mechanical advantage is equal to velocity ratio
(c) mechanical advantage is less than velocity ratio
(d) mechanical advantage is unity
(e) none of the above.
Ans: b
136. A cable with a uniformly distributed load per
horizontal meter run will take the following shape
(a) straight line
(b) parabola
(c) hyperbola
(d) elliptical
(e) part of a circle.
Ans: b

Fluid Mechanics interviewquestions and answers

1. Why the Centrifugal Pump is called High Discharge pump?
Centrifugal pump is a kinetic device. The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate. It is given in the following
formulae:
Centrifugal force F= (M*V2)/R.
Where, M-Mass;  V-Velocity; R-Radius

2. How Cavitation can be eliminated by Pump?
Cavitation means bubbles are forming in the liquid. ·
To avoid Cavitation, we have to increase the Pump size to One or Two Inch;
To increase the pressure of the Suction Head, or  Decrease the Pump Speed.

3. Why Cavitation will occur in Centrifugal Pump and not in Displacement Pump?
The formation of cavities (or bubbles) is induced by flow separation, or non-uniform flow velocities, inside a pump casing. In centrifugal pumps the eye of the pump impeller is smaller than the flow area of pipe. This decrease in flow area of pump results in increase in flow rate. So pressure drop happened between pump suction and the vanes of the impeller. Here air bubbles or cavities are formed because of liquid vapour due to increase in temperature in impeller. This air bubbles are transmitted to pump which forms cavitation.

4. Which Pump is more Efficient Centrifugal Pump or Reciprocating Pump?

Centrifugal pump. Because flow rate is higher compared to reciprocating pump. Flow is smooth and it requires less space to install. Lower initial cost and lower maintenance cost.

5. Why Centrifugal Pump is not called as a Positive Displacement Type of Pump?

The centrifugal has varying flow depending on pressure or head, whereas the Positive Displacement pump has more or less constant flow regardless of pressure.
Likewise viscosity is constant for positive displacement pump where centrifugal pump have up and down value because the higher viscosity liquids fill the clearances of the pump causing a higher volumetric efficiency. When there is a viscosity change in supply there is also greater loss in the system. This means change in pump flow affected by the pressure change. One more example is, positive displacement pump has more or less constant efficiency, where centrifugal pump has varying efficiency rate.

6. How Cavitation can be eliminated in a Pump?
Cavitation means bubbles are forming in the liquid.
· To avoid Cavitation, we have to increase the Pump size to One or Two Inch;
· To increase the pressure of the Suction Head, or
· Decrease the Pump Speed.

7. Which pump is more efficient Centrifugal pump or Reciprocating pump?
Centrifugal pump. Because flow rate is higher compared to reciprocating pump. Flow is smooth and it requires less space to install. Lower initial cost and lower maintenance cost.

8. Why Centrifugal Pump is not called as a Positive Displacement Type of Pump?
The centrifugal has varying flow depending on pressure or head, whereas the Positive Displacement pump has more or less constant flow regardless of pressure.  Likewise viscosity is constant for positive displacement pump where centrifugal pump have up and down value because the higher viscosity liquids fill the clearances of the pump causing a higher volumetric efficiency. When there is a viscosity  change in supply there is also greater loss in the system. This means change in pump flow affected by the pressure change. One more example is, positive displacement pump has more or less constant efficiency, where centrifugal pump has varying efficiency rate.

9. What is a radial-flow turbine?
In a radial-flow turbine, steam flows outward from the shaft to the casing. The unit is usually a reaction unit, having both fixed and moving blades.

10. What are four types of turbine seals?
Carbon rings fitted in segments around the shaft and held together by garter or retainer springs. Labyrinth mated with shaft serration’s or shaft seal strips. Water seals where a shaft runner acts as a pump to create a ring of water around the shaft. Use only treated water to avoid shaft pitting. Stuffing box using woven or soft packing rings that are compressed with a gland to prevent leakage along the shaft.

11. What are two types of clearance in a turbine?
Radial – clearance at the tips of the rotor and casing.
Axial – the fore-and-aft clearance, at the sides of the rotor and the casing.

12. What is the function of a thrust bearing?
Thrust bearings keep the rotor in its correct axial position.

13. What is a stage in a steam turbine?  In an impulse turbine, the stage is a set of moving blades behind the nozzle. In a reaction turbine, each row of blades is called a "stage." A single Curtis stage may consist of two or more rows of moving blades.

14. What is a diaphragm?
Partitions between pressure stages in a turbine’s casing are called diaphragms. They hold the vane- shaped nozzles and seals between the stages. Usually labyrinth-type seals are used. One-half of the diaphragm is fitted into the top of the casing, the other half into the bottom.

15. What are the two basic types of steam turbines?
Impulse type. Reaction type.

16. What are topping and superposed turbines?Topping and superposed turbines arc high- pressure, non-condensing units that can be added to an older, moderate-pressure plant. Topping turbines receive high-pressure steam from new high-pressure boilers. The exhaust steam of the new turbine has the same pressure as the old boilers and is used to supply the old turbines.

17. What is a combination thrust and radial bearing?
This unit has the ends of the Babbitt bearing extended radically over the end of the shell. Collars on the rotor face these thrust pads, and the journal is supported in the bearing between the thrust collars.