About Machine Design

Following are some of the multiple choice questions on the Machine Design with answers that will help the students in developing their knowledge.

Machine Design MCQ

1. The stress induced in the belt is,

  • Tensile stress
  • Compressive stress
  • Direct shear stress
  • Torsional shear stress

2. A key way lowers

  • The strength of the shaft
  • The rigidity of the shaft
  • Both the strength and rigidity of the shaft
  • The ductility of the shaft

3. The rocker arms in internal combustion engines are of__________.

  • First type levers
  • Second type levers
  • Third type levers
  • None of these

4. A steel containing 0.8% carbon is known as

  • Eutectoid steel
  • Hypereutectoid steel
  • Hypo-eutectoid steel
  • None of these

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

  • Mild steel
  • Dead mild steel
  • Medium carbon steel
  • High carbon steel

6. 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

  • 5 N-m
  • 7 N-m
  • 10 N-m
  • 15 N-m

7. The ratio of driving tensions for flat belts, neglecting centrifugal tension, is (where T₁, and T₂ = Tensions on the tight and slack sides of belt respectively, μ = Coefficient of friction, between the belt and pulley, and θ = Angle of contact)

  • T₁/T₂ = μθ
  • log (T₁/T₂) = μθ
  • T₁/T₂ =eμθ
  • T₁/T₂ = log μθ

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

  • Strength
  • Stiffness
  • Brittleness
  • Toughness

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

  • Electroplating
  • Polishing
  • Coating
  • Shot peening

10. An alien bolt is

  • Self locking bolt
  • Same as stud
  • Provided with hexagonal depression in head
  • Used in high speed components

11. Rivets are generally specified by

  • Thickness of plates to be riveted
  • Length of rivet
  • Diameter of head
  • Nominal diameter

12. Allen bolts are

  • Self locking bolts
  • Designed for shock load
  • Used in aircraft application
  • Provided with hexagonal depression in head

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

  • Elastic limit
  • Ultimate tensile strength
  • Young's modulus
  • Endurance limit

14. Resistance to fatigue of a material is measured by

  • Young's modulus
  • Coefficient of elasticity
  • Elastic limit
  • Endurance limit

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

  • 10
  • 15
  • 20
  • 25

16. In replacing the V-belts, a complete set of new belts is used instead of replacing a single damaged belt because

  • Belts are available in sets
  • Only one belt cannot be fitted with other used belts
  • The new belt will carry more than its share and result in short life
  • New and old belts will cause vibrations

17. A tapered key which fits in a key way in the hub and the bottom of which is shaped to fit the curved surface of the shaft, is known as,

  • Hollow saddle key
  • Hollow key
  • Soft key
  • None of these

18. The material generally used for aircraft components is

  • Mild steel
  • High speed steel
  • Stainless steel
  • Aluminium

19. Which of the following has threads at both ends?

  • Bolt
  • Tap bolt
  • Stud
  • None of these

20. When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor, and W = Axial compressive load on the spring)

  • (WD/ πd3) × K
  • (2WD/ πd3) × K
  • (4WD/ πd3) × K
  • (8WD/ πd3) × K

21. For tight leakage joints, following type of thread is best suited

  • Metric
  • Buttress
  • Square
  • NPT (national pipe threads).

22. The rolling contact bearings as compared to sliding contact bearings have

  • Low starting and low running friction except at very high speeds
  • Accuracy of shaft alignment
  • Small overall dimensions
  • All of the above

23. Machine screws are

  • Similar to small size tap bolts except that a greater variety of shapes of heads are available
  • Slotted for a screw driver and generally used with a nut
  • Used to prevent relative motion between two parts
  • Similar to stud

24. A woodruff key is

  • A tapered key with head at one end
  • Fitted in pairs at right angles
  • Capable of tilting in a recess milled out in the shaft
  • All of the above

25. A tap bolt

  • Has a head on one end and a nut fitted to the other
  • Has head at one end and other end fits into a tapped hole in the other part to be joined
  • Has both the ends threaded
  • Has pointed threads

26. A stud

  • Has a head on one end and a nut fitted to the other
  • Has head at one end and other end fits into a tapped hole in the other part to be joined
  • Has both the ends threaded
  • Has pointed threads

27. The velocity factor for precision metallic gears cut with high accuracy and operating at velocities up to 20 m/s is equal to

  • 0.75/ (0.75 + √v)
  • 3/ (3 + v)
  • 4.5/ (4.5 + v)
  • 6/ (6 + v)

28. A double fillet welded joint with parallel fillet weld of length 'l' and leg 's' is subjected to a tensile force 'P'. Assuming uniform stress distribution, the shear stress in the weld is given by

  • √2P/s.l
  • P/2.s.l
  • P/√2.s.l
  • 2P/s.l

29. A plate with an elliptical hole in the centre, with semi-major axis (a) perpendicular to the direction of loading and semi-minor axis (b) along the direction of loading, is subjected to a pull P. The maximum stress induced at the edge of the hole is equal to (where σ = Stress for a plate with no hole i.e. nominal stress)

  • σ [1 + (b/2a)]
  • σ [1 + (2a/b)]
  • σ [1 + (b/3a)]
  • σ [1 + (3a/b)]

30. Two shafts ‘A’ and ‘B’ under pure torsion are of identical length and identical weight and are made of the same material. The shaft ‘A’ is solid and the shaft ‘B’ is hollow. We can say that

  • Shaft B is better than shaft A
  • Shaft A is better than shaft B
  • Both the shafts are equally good
  • None of these

31. 18/8 steel contains

  • 18% nickel and 8% chromium
  • 18% chromium and 8% nickel
  • 18% nickel and 8% vanadium
  • 18% vanadium and 8% nickel

32. In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.

  • Larger than
  • Smaller than
  • Equal to
  • None of these

33. Two shafts A and B are made of the same material. The diameter of shaft A is twice as that of shaft B. The power transmitted by the shaft A will be __________ of shaft B.

  • Twice
  • Four times
  • Eight times
  • Sixteen times

34. A riveted joint is a __________ fastening.

  • Permanent
  • Temporary
  • Either A or B
  • None of these

35. The expansion joint is mostly used for pipes which carry steam at __________ pressures.

  • Low
  • High
  • Medium
  • None of these

36. The V-belts are particularly suitable for __________ drives.

  • Short
  • Long
  • Both A and B
  • None of these

37. A crankshaft is a __________ shaft.

  • Transmission
  • Machine
  • Machine frame
  • None of these

38. A single strap butt joint is always in __________ shear.

  • Single
  • Double
  • Triple share
  • None of these

39. The dedendum circle diameter is equal to (where φ = Pressure angle)

  • Pitch circle diameter × cosφ
  • Addendum circle diameter × cosφ
  • Clearance circle diameter × cosφ
  • Pitch circle diameter × sinφ

40. A bolt

  • Has a head on one end and a nut fitted to the other
  • Has head at one end and other end fits into a tapped hole in the other part to be joined
  • Has both the ends threaded
  • Is provided with pointed threads

41. Basic shaft is one

  • Whose upper deviation is zero
  • Whose lower deviation is zero
  • Whose lower as well as upper deviations are zero
  • Does not exist

42. Which of the following cotter joint will be used to connect strap end of a connecting rod?

  • Spigot and socket cotter joint
  • Sleeve and cotter joint
  • Gib and cotter joint
  • Any one of these

43. Which of the following statement is wrong for a connecting rod?

  • The connecting rod will be equally strong in buckling about X-axis and Y-axis, if Ixx = 4 Iyy
  • If Ixx > 4 Iyy, the buckling will occur about Y-axis
  • If Ixx
  • The most suitable section for the connecting rod is T-section

44. Which of the following formula is used in designing a connecting rod?

  • Euler's formula
  • Rankine's formula
  • Johnson's straight line formula
  • Johnson's parabolic formula

45. The resultant axial load on a bolt depends on

  • Initial tension
  • External load applied
  • Relative elastic yielding (springness) of the bolt and the connected member
  • All of the above

46. A bolt of M 24 × 2 means that

  • The pitch of the thread is 24 mm and depth is 2 mm
  • Cross-sectional area of the threads is 24 mm²
  • The nominal diameter of bolt is 24 mm and pitch is 2 mm
  • The effective diameter of bolt is 24 mm and there are 2 threads per cm

47. According to Indian standard specifications, a Grey cast iron designated by 'FG 200' means that the

  • Carbon content is 2%
  • Maximum compressive strength is 200 N/mm²
  • Minimum tensile strength is 200 N/mm²
  • Maximum shear strength is 200 N/mm²

48. The designation M 33 × 2 of a bolt means

  • Metric threads of 33 numbers in 2 cm
  • Metric threads with cross-section of 33 mm
  • Metric threads of 33 mm outside diameter and 2 mm pitch
  • Bolt of 33 mm nominal diameter having 2 threads per cm

49. Which one of the following is a positive drive?

  • V-belt drive
  • Rope drive
  • Crossed flat belt drive
  • Chain drive

50. The velocity factor for ordinary cut gears operating at velocities up to 12.5 m/s is equal to

  • 0.75/(0.75 + √v)
  • 3/(3 + v)
  • 4.5/(4.5 + v)
  • 6/(6 + v)

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