Machine design - Mechanical Engineering test questions

Machine design - Mechanical Engineering test questions

1) Which of the following types of threads would be best suited for applications involving high stresses in one direction?

a) Buttress threads
b) Square threads
c) Knuckle threads
d) V-threads

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2) As compared to sliding bearings, ball and roller bearing have

a) More accuracy in alignment
b) Small overall dimensions
c) Low starting and running friction
d) All of these

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3) The stress concentration factor is

a) It is the ratio of maximum stress to the nominal stress
b) It is the ratio of nominal stress to the maximum stress
c) It is the ratio of maximum stress to the endurance limit
d) It is the ratio of nominal stress to the endurance limit

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4) When a body is suddenly loaded the strain energy stored in it is ……….the strain energy stored when the load is applied gradually on the body

a) Three times
b) Twice
c) Four times
d) Equal to

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5) ……………is not the characteristic of the spherical roller bearings

a) High load capacity
b) Self aligning capability
c) High operational speed
d) High tolerance to shock loads

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6) Lewis correlation is used to determine

a) Compressive stress in bending
b) Shear stress
c) Tensile stress in bending
d) Fatigue stress

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7) The brakes that are commonly used in railway trains are

a) Shoe brake
b) Internal expanding brake
c) Band brake
d) Band and block brake

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8) In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to teeth is called as

a) Diametral pitch
b) Axial pitch
c) Normal pitch
d) None of these

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9) Which among the following statement is correct regarding a ‘stud’?

a) It has both the ends threaded
b) It requires locking nuts
c) It has a head on one end and a nut fitted on the other
d) None of these

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10) The rated life of a bearing varies

a) Inversely as fourth power of load
b) Inversely as cube of load
c) Inversely as square of load
d) Directly as load

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11) The shock absorbing capacity of a bolt can be increased by

a) Using washer
b) Tightening it properly
c) Grinding the shank
d) Making shank diameter equal to core diameter of thread

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12) A helical compression spring is cut into two halves. What is the stiffness of the resulting spring?

a) One-half
b) Same
c) Double
d) One-fourth

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13) Slenderness ratio is the ratio of

a) Effective length of column to width of column
b) Maximum size of a column to minimum size of column
c) Effective length of a column to least radius of gyration of the column
d) Width of column to depth of column

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14) Angle of twist of a shaft is inversely proportional to

a) D²
b) d^3/2
c) d³
d) d⁴

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15) Low pressure angle gears results in

a) Pressure angle does not affect strength
b) Stronger teeth
c) Weaker teeth
d) None of these

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16) Which of the following statement is correct regarding centrifugal tension in the belt?

a) It decreases the horse power transmitted
b) It has no effect on the power transmitted
c) It increases the horse power transmitted
d) It is equal to maximum tension in the belt

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17) According to IBR the riveted point for circumferential joint boilers is of the type

a) Butt joint with double cover plate
b) Butt joint with single cover plate
c) Lap joint with one ring overlapping the other
d) Single riveted lap joint

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18) Among the following which statement is incorrect?

a) In case of lap joints and butt joint with single cover strap, the rivet will be in single shear
b) In case of butt joints with double cover straps, the rivet will be in double shear
c) The thickness of the straps in a butt joint, according to IBR, should not be less than 10mm
d) A butt joint with two cover plates should be used for circumferential joint in boilers

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19) In thrust bearings the load acts

a) Perpendicular to the axis of rotation
b) Along the axis of rotation
c) Parallel to the axis of rotation
d) None of these

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20) Plastic bearings in preference to metals, are being increasingly used in applications involving

a) High temperatures
b) Frequent starting and stopping
c) Creep under load conditions
d) Minimum frequency of oscillations

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21) …………..type of joint is used for longitudinal joint in boilers

a) Lap joint with one ring overlapping the other
b) Butt joint with double cover plate
c) Butt joint with single cover plate
d) None of these

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22) A material is said to fail under fatigue when it fails

a) Below the yield point
b) Below the elastic limit
c) At the yield point
d) At the elastic limit

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23) In the Lewis equation the working stress depends upon

a) Tooth material only
b) Pitch line velocity only
c) Pitch line velocity, load conditions and tooth material
d) The load conditions and tooth material

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24) The greatest twisting moment which a shaft can resist is given by

a) Maximum shear stress x polar modulus
b) Maximum shear stress x modulus of rigidity
c) Modulus of rigidity / polar moment of inertia
d) Torsional rigidity of the shaft

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25) Helix angle will be ………..if the lead angle of a worm is 20°

a) 70°
b) 15°
c) 55°
d) 30°

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26) How does the pressure angle changes, when the centre distance of the mating gears having involute teeth is increased?

a) It remains unchanged
b) It increases
c) It decreases
d) It is unpredictable

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27) The resilience of a bolt may be increased by

a) Decreasing its length
b) Increasing its length
c) Decreasing its shank diameter
d) Increasing its shank diameter

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28) The critical speed of a shaft is affected by …………………parameters

a) Diameter of the disc
b) Span of the shaft
c) Eccentricity
d) All of these

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29) The selection of material for gears depend on ………………… factors

a) Peripheral speed
b) Shock and wear resistance
c) Required dimensions and weight of the drive
d) All of these

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30) Life of a rolling bearing as listed in a catalogue is usually

a) Maximum expected life
b) Minimum expected life
c) Mean life
d) None of these

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31) Why are concentric helical springs wound in opposite direction?

a) To maintain identical stiffness in both the springs
b) To avoid unequal deflection in the two springs
c) To maintain identical shear stress in the two springs
d) To avoid binding of adjacent coils

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32) Teflon is used for bearings when

a) Low co-efficient of friction is desired
b) Heat dissipation is a problem
c) Space is the major consideration
d) Bearings operate at very high speed

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33) In journal bearings L/D ratio seldom exceeds 2 due to

a) Economic considerations
b) Heat dissipation problems
c) Risk of metal to metal contact
d) All of these

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34) Fillers like graphite and molybdenum disulphide are used mainly in nylon bearings

a) To assist in heat dissipation
b) To reduce frictional losses
c) To provide porous bearing media for vibration absorption
d) To improve mechanical and lubricating properties

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35) The contact ratio of two meshing gears is

a) It is the ratio of length of the arc of approach to arc of recess
b) It is the ratio of length of the arc of contact to the circular pitch
c) It is the ratio of length of the arc of contact to the circular pitch
d) None of these

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36) Lowest value of joint efficiency is assumed for

a) Single cover double row butt joint
b) Double cover double row butt joint
c) Single row lap joint
d) Double row lap joint

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37) Partial journal bearing is known as clearance bearing due to

a) Diameter of the journal is less than the diameter of the bearing
b) Angle of contact of the journal with bearing is less than 360°
c) Both (a) and (b)
d) None of these

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38) The working depth of a gear is equal to

a) Distance between clearance circle and addendum circle
b) Addendum + dedendum
c) Addendum – dedendum
d) None of these

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39) Viscosity index is used to denote the degree of variation of viscosity with

a) Pressure
b) Temperature
c) Humidity
d) None of these

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40) For which of the following reasons is multiple threads employed?

a) High load lifting capacity
b) High mechanical advantage
c) High efficiency
d) None of these

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