Design of Machine Elements Objective Questions and Answers Pdf Download

1. According to Indian standards, total numbers of fundamental deviations are

A. 10

B. 15

C. 20

D. 25

Answer: Option D

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2. Resistance to fatigue of a material is measured by

A. Young's modulus

B. Coefficient of elasticity

C. Elastic limit

D. Endurance limit

Answer: Option D

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3. The resistance to fatigue of a material is measured by

A. Elastic limit

B. Ultimate tensile strength

C. Young's modulus

D. Endurance limit

Answer: Option D

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4. Allen bolts are

A. Self locking bolts

B. Designed for shock load

C. Used in aircraft application

D. Provided with hexagonal depression in head

Answer: Option D

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5. Rivets are generally specified by

A. Thickness of plates to be riveted

B. Length of rivet

C. Diameter of head

D. Nominal diameter

Answer: Option D

Design of Machine Elements Objective Questions and Answers Pdf Download

6. The size of a gear is usually specified by

A. Pressure angle

B. Pitch circle diameter

C. Circular pitch

D. Diametral pitch

Answer: Option B

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7. 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

Answer: Option C

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8. The fatigue life of a part can be improved by

A. Electroplating

B. Polishing

C. Coating

D. Shot peening

Answer: Option D

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9. Which of the following property is desirable in parts subjected to shock and impact loads?

A. Strength

B. Stiffness

C. Brittleness

D. Toughness

Answer: Option D

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Design of Machine Elements Objective Questions and Answers Pdf Download

11. A spring of stiffness 1000 N/m is stretched initially by 100 mm from the undeformed position. The work required to stretch it by another 100 mm is

A. 5 N-m

B. 7 N-m

C. 10 N-m

D. 15 N-m

Answer: Option D

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12. A steel containing up to 0.15% carbon is known as

A. Mild steel

B. Dead mild steel

C. Medium carbon steel

D. High carbon steel

Answer: Option B

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13. A steel containing 0.8% carbon is known as

A. Eutectoid steel

B. Hypereutectoid steel

C. Hypo-eutectoid steel

D. None of these

Answer: Option A

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14. The rocker arms in internal combustion engines are of __________.

A. First type levers

B. Second type levers

C. Third type levers

D. None of these

Answer: Option A

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15. Gears are casted by

A. Sand mould casting

B. Slush casting

C. Permanent mould casting

D. Centrifugal casting

Answer: Option C

Design of Machine Elements Objective Questions and Answers Pdf Download

16. 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

Answer: Option A

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17. Which of the following statement is wrong?

A. The solid length of a spring is the product of total number of coils and the diameter of the wire

B. The spring index is the ratio of mean diameter of the coil to the diameter of the wire

C. The spring stiffness is the load required per unit deflection of the spring

D. The pitch of the coil is the axial distance between adjacent coils in the compressed state

Answer: Option D

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18. Which of the following statement is wrong?

A. The V-belt may be operated in either direction with tight side of the belt at the top or bottom

B. The V-belt drive is used with large center distance

C. The power transmitted by V-belts is less than flat belts for the same coefficient of friction, arc of contact and allowable tension in the belts

D. The ratio of driving tensions in V-belt drive is more than flat belt drives

Answer: Option B

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19. Which of the following statement is wrong?

A. The pitch of rivets is obtained by equating the tearing resistance of the plate to the shearing resistance of the rivets

B. The pitch of rivets should not be less than 2d, where d is the diameter of rivet hole

C. The maximum value of the pitch of rivets for a longitudinal joint of a boiler, as per I.B.R., is given by Pmax = C.t + 41.28 mm

D. According to I.B.R., the thickness of butt strap shall not be less than 5 mm

Answer: Option D

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20. Which of the following statement is wrong?

A. A key is used as a temporary fastening

B. A key is subjected to tensile stresses

C. A key is always inserted parallel to the axis of the shaft

D. A key prevents relative motion between the shaft and boss of the pulley

Answer: Option B

Design of Machine Elements Objective Questions and Answers Pdf Download

21. In most machine members, the damping capacity of the material should be

A. Low

B. Zero

C. High

D. Could be anything

Answer: Option C

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22. Which of the following bearing is preferred for oscillating conditions?

A. Double row roller bearing

B. Taper roller bearing

C. Angular contact single row ball bearing

D. Needle roller bearing

Answer: Option D

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23. The contact ratio for gears is

A. Zero

B. Less than one

C. Greater than one

D. None of these

Answer: Option C

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24. Which of the following material has the maximum ductility?

A. Copper

B. Mild steel

C. Aluminium

D. Zinc

Answer: Option B

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25. In radial bearings, the load acts __________ to the axis of rotation.

A. Parallel

B. Perpendicular

C. Both A and B

D. None of these

Answer: Option B

Design of Machine Elements Objective Questions and Answers Pdf Download

26. 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

Answer: Option B

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27. Tapered roller bearings can take

A. Axial load only

B. Both radial and axial loads and the ratio of these being greater than unity

C. Radial load only

D. Both radial and axial loads and the ratio of these being less than unity

Answer: Option B

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28. The power transmitted by means of a belt depends upon

A. Velocity of the belt

B. Tension under which the belt is placed on the pulleys

C. Arc of contact between the belt and the smaller pulley

D. All of the above

Answer: Option D

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29. In a multiple V-belt drive, if one of the belts break, then

A. Only the broken belt is replaced

B. The entire set of belts is replaced

C. The broken belt and the belt on either side of it, is replaced

D. The broken belt need not to be replaced

Answer: Option B

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30. The resultant axial load on a bolt depends upon

A. External load applied

B. Initial tension due to tightening of the bolt

C. Relative elastic yielding of the bolt and the connected members

D. All of the above

Answer: Option D

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31. The process extensively used for making bolts and nuts is

A. Hot piercing

B. Extrusion

C. Cold peening

D. Cold heading

Answer: Option D

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32. In a marine flange coupling, the pitch circle diameter of bolts is taken as

A. 1.2 d

B. 1.6 d

C. 2 d

D. 2.5 d

Answer: Option B

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33. A sliding bearing in which although lubricant is present, the working surfaces __________ contact each other at least part of the time, is called boundary lubricated bearing.

A. Partially

B. Fully

C. Either A or B

D. None of these

Answer: Option A

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34. In a steam engine, the valve rod is connected to an eccentric rod by means of

A. Cotter joint

B. Knuckle joint

C. Universal joint

D. Flange coupling

Answer: Option B

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35. An elastic bar is fixed at the upper end and loaded at the lower end by a falling weight. The shock load produced can be reduced by

A. Increasing the length of bar

B. Decreasing the cross-sectional area of the bar

C. Decreasing the modulus of elasticity of the bar

D. All of the above

Answer: Option D

Design of Machine Elements Objective Questions and Answers Pdf Download

36. 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 between parts

D. Provided with detachable caps

Answer: Option A

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37. All stresses produced in a belt are

A. Compressive stresses

B. Tensile stresses

C. Both tensile and compressive stresses

D. Shear stresses

Answer: Option B

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38. The included angle for the British Association thread is

A. 29°

B. 55°

C. 47.3°

D. 60°

Answer: Option C

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39. The difference between the tooth space and the tooth thickness as measured on the pitch circle, is called

A. Working depth

B. Clearance

C. Backlash

D. Face width

Answer: Option C

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40. In nitrated parts, the origins of the fatigue cracks will occur at

A. Surface

B. Just below the surface

C. Within the core

D. None of the above

Answer: Option D

Design of Machine Elements Objective Questions and Answers Pdf Download

41. 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

Answer: Option A

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42. A closely coiled helical spring is acted upon by an axial force. The

maximum shear stress developed in the spring is . The half of the length of the spring if cut off and the remaining spring is acted upon by the same axial force. The maximum shear stress in the spring in the new condition will be

A. τ/2

B. τ

C. 2τ

D. 4τ

Answer: Option B

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43. The shock resistance of steel is increased by adding

A. Nickel

B. Chromium

C. Nickel and chromium

D. Cobalt and molybdenum

Answer: Option C

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44. While designing a screw in a screw jack against buckling failure, the end conditions for the screw are taken as

A. Both the ends fixed

B. Both the ends hinged

C. One end fixed and the other end hinged

D. One end fixed and the other end free

Answer: Option D

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45. At low temperatures (say 75°C) the notched bar impact value of steel

A. Increases markedly

B. Decreases markedly

C. Remain same

D. Depends on heat treatment carried out

Answer: Option B

Design of Machine Elements Objective Questions and Answers Pdf Download

46. Which of the following statement is correct, for two shafts connected in parallel?

A. Torque in each shaft is the same

B. Shear stress in each shaft is the same

C. Angle of twist of each shaft is the same

D. Torsional stiffness of each shaft is the same

Answer: Option C

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47. The value of stress concentration factor depends upon

A. Material and geometry of the part

B. Geometry of the part

C. Material of the part

D. None of these

Answer: Option D

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48. 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

Answer: Option C

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49. Stress concentration factor is defined as the ratio of

A. Maximum stress to the endurance limit

B. Nominal stress to the endurance limit

C. Maximum stress to the nominal stress

D. Nominal stress to the maximum stress

Answer: Option C

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50. 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. 124 d

B. 138 d

C. 151 d

D. 168 d

Answer: Option D

Design of Machine Elements Objective Questions and Answers Pdf Download

51. Shaft coupling is used in machinery to

A. Introduce mechanical flexibility

B. Introduce protection against over loads

C. Reduce the transmission of shock loads

D. All of these

Answer: Option D

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52. The stress induced in the belt is,

A. Tensile stress

B. Compressive stress

C. Direct shear stress

D. Torsional shear stress

Answer: Option A

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53. A connecting rod subjected to an axial load may buckle with

A. X-axis as neutral axis

B. Y-axis as neutral axis

C. X-axis or Y-axis as neutral axis

D. Z-axis

Answer: Option C

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54. Wire ropes as compared to cotton ropes

A. Are lighter in weight

B. Offer silent operation

C. Can withstand shock loads

D. All of these

Answer: Option D

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55. In the calculation of induced shear stress in helical springs, the Wahl's stress factor is used to take care of

A. Combined effect of transverse shear stress and bending stress in the wire

B. Combined effect of bending stress and curvature of the wire

C. Combined effect of transverse shear stress and curvature of wire

D. Combined effect of torsional shear stress and transverse shear stress in the wire

Answer: Option B

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Design of Machine Elements Objective Questions and Answers Pdf Download