machine design Mcqs
51. The endurance limit of a material with finished surface in comparison to rough surface is_________________?
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A. more or less depending on quantum of load

B. more

C. less

D. unpredictable

E. same

52. At low temperatures (say 75C) the notched-bar impact value of steel____________________?
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A. depends on heat treatment carried out

B. none of the above

C. remains same

D. decreases markedly

E. increases markedly

53. Applications in which stresses are encountered in one direction only uses following type of threads____________________?
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A. BSW

B. metric

C. square

D. buttress

E. acme

54. Oil in journal bearing should be applied at the point where load is________________?
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A. maximum

B. unpredictable

C. average

D. nil or lightest

E. any one of the above

55. The edges of the plates for cylindrical vessels are usually bevelled to an angle of 80 for_________________?
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A. reducing stress concentration

B. all of the above

C. safety

D. ease of manufacture

E. fullering and caulking
56. The connecting rod bolts are tightened up so that tightening stress _________________?
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A. is about yield point divided by safety factor

B. none of the above

C. approaches yield point

D. is just sufficient to hold parts together

E. is 50% of yield point

57. Resistance to fatigue of a material is measured by________________?
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A. Youngs modulus

B. endurance limit

C. ultimate tensile strength

D. elastic limit

E. coefficient of elasticity

58. The valve rod in a steam engine is connected to an eccentric rod by_________________?
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A. universal coupling

B. kunckle joint

C. gib and cotter joint

D. cotter joint

E. bolted joint

59. Fatigue strength can be increased by__________________?
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A. cold working

B. hot working

C. shot peening

D. using gradual changes of section

E. grinding and lapping surface

60. 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_________________?
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A. 20Vdto30Vd

B. 30V5?to40Vd

C. lOVZ

D. 10VZtol5Vd

E. 15Vdto20VZ

61. Fibrous fracture occurs in_____________?
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A. hard material

B. brittle material

C. ductile material

D. elastic material

E. all of the above

62. Which of the following pipe joints would be suitable for pipes carrying steam_____________?
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A. threaded

B. flanged

C. compression

D. expansion

E. bell and spigot

63. Other method of reducing shock load in the above case can be_________________?
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A. unaffected by length

B. to increase length

C. none of the above

D. to decrease length

E. other factors would decide same

64. Plastic flow in ductile materials_____________________?
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A. depends on other considerations

B. lessens the seriousness of static loading stress concentration

C. none of the above

D. increases the seriousness of static load-ing stress concentration

E. has no effect on it

65. Turn buckle has____________________?
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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

66. Belt slip may occur due to________________?
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A. loose belt

B. driving pulley too small

C. all of the above

D. none of the above

E. heavy load

67. Stress concentration in cyclic loading is____________________?
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A. ch is correct statement ?

B. very serious in brittle materials and less serious in ductile materials

C. very serious in ductile materials and less serious in brittle materials

D. equally serious in both types of materials

E. seriousness would depend on other factors

F. none of the above

68. A bolt___________________?
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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

69. Castle nut is a locking device in which__________________?
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A. 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

B. a slot is cut partly is middle of nut and then slot reduced by tightening a screw

C. one smaller nut is tightened over main nut and main nut tightened against smaller one by loosening, creating friction jamming

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.

70. Gear box is used___________________?
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A. to obtain variable speeds

B. for speed reduction

C. to damp out vibrations

D. to increase efficiency of system

E. to produce torque

71. A key made from a cylindrical disc having segmental cross-section, is known as______________?
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A. feather key

B. hollow saddle key

C. flat saddle key

D. gib head key

E. wood-ruff key
72. Brittle coating technique is used for_________________?
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A. protecting metal against corrosion

B. determining brittleness

C. protecting metal against wear and tear

D. non-destructive testing of metals

E. experimental stress analysis
73. 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________________?
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A. 0.7 times

B. 0.8 times

C. 0.4 times

D. 0.6 times

E. 0.9 times the normal diameter of bolt

74. Form coefficient of spring is _____________________?
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A. load required to produce unit deflection

B. its capability of storing energy

C. concerned With strength of wire of spring

D. ratio of coil diameter to wire diameter

E. nothing

75. Ball bearing type screws are found in following application_____________________?
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A. aeroplane engines

B. bench vice

C. steering mechanism

D. crane

E. screw jack

76. The shock absorbing capacity of a bolt can be increased by___________________?
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A. tightening it properly

B. grinding the shank

C. making shank diameter equal to core diameter of thread

D. increasing shank diameter

E. using washer

77. The property of a material which enables it to resist fracture due to high impact loads is known as__________________?
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A. endurance

B. strength

C. elasticity

D. toughness

E. resilience

78. Cap screws are___________________?
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A. slotted for a screw driver and generally used with a nut

B. similar to stud

C. used to prevent relative motion be-tween parts

D. similar tosmall size tap bolts except that a greater variety of shapes of heads are available

E. provided with detachable caps

79. The building up of worn and uridersized parts, subjected to repeated loads by electroplating is_____________________?
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A. best method

B. extremely hazardous

C. cheapest method

D. has no effect as regards fatigue strength

E. all of the above

80. When a close coiled helical spring is compressed, its wire is subjected to________________?
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A. shear

B. compression

C. all of the above

D. tension

E. none of the above

81. Stress concentration in static loading is_________________?
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A. ch is correct statement ?

82. Machine screws are________________?
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A. used to prevent relative motion be-tween two parts

B. none of the above

C. similar to stud

D. slotted for a screw driver and generally used with a nut

E. similar to small size tap bolts except that a greater variety of shapes of heads are available

83. 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__________________?
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A. 1.75 d

B. 2 d.

C. 1.5 d

D. d

E. 1.25 d

84. The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is_________________?
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A. larger

B. equal

C. smaller

D. larger/smaller depending on diameter of spring coil

E. unpredictable

85. 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_______________?
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A. 138 d

B. 168 d

C. 151 d

D. 124 d

E. 102 d

86. When two springs are in series (having stiffness K), the equivalent stiffness will be________________?
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A. 2K

B. UK

C. K/2

D. KIA

E. K

87. Spring stiffness is__________________?
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A. its capability of storing energy

B. ratio of coil diameter to wire diameter

C. none of the above

D. its ability to absorb shocks

E. load required to produce unit deflection
88. If shearing stress in nut is half the tensile stress in a bolt, then nut length should be equal to___________________?
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A. 1.25 x diameter of bolt

B. 1.5 x diameter of bolt

C. diameter of bolt

D. 0.5 x diameter of bolt

E. 0.75 x diameter of bolt

89. 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_________________?
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A. would depend upon other factors

B. decreasing the cross-section area of bar

C. increasing the cross-section area of bar

D. remain unaffected with cross-section area

E. none of the above

90. In Vickers hardness testing, the pyramid indentor apex is__________________?
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A. 40

B. 122

C. 152

D. 136

E. 161.

91. Rankines theory of failure is applicable for following type of materials___________________?
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A. ductile

B. tough

C. brittle

D. plastic

E. elastic

92. The edges of a boiler plate are bevelled to an angle of______________?
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A. 60

B. 45

C. 85.

D. 30

E. 80
93. In oilness bearings________________?
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A. grease required to be applied after some intervals

B. do not require external supply of lubricant

C. the oil film pressure is generated only by the rotation of the journal

D. none of the above

E. the oil film is maintained by supplying oil under pressure

94. Resilience of a material is important, when it is subjected to________________?
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A. combined loading

B. thermal stresses

C. fatigue

D. shock loading

E. wear and tear

95. For tight leakage joints, following type of thread is best suited ____________________?
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A. square

B. buttress

C. NPT (national pipe threads)

D. metric

E. acme

96. The usual clearance provided in hydrodynamic bearing per mm of diameter of shaft is___________________?
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A. 1 micron

B. 0.1 micron

C. 10 microns

D. 25 microns

E. 0.01 micron

97. Yield point in fatigue loading as compared to static loading is__________________?
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A. same

B. depends on other factors

C. lower

D. none of the above

E. higher

98. The included angle in unified of American National threads is___________________?
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A. 29

B. 47

C. none of the above

D. 60

E. 55

99. In order to permit the thermal expansion/contraction of tubing, it should be______________?
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A. honed

B. crimped

C. bent

D. none of the above

E. flared

100. If two springs are in parallel then their overall stiffness will be_______________?
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A. double

B. none of the above

C. unpredictable

D. same

E. half