NDA - Machine Design 1000+ MCQ [Solved] PDF Download

1. The constant factor in case of R10 series of preferred numbers is
A. 1.06
B. 1.12
C. 1.26
D. 1.58
Answer : C

2. The ratio of the ultimate stress to the design stress is known as
A. Elastic limit
B. Strain
C. Factor of safety
D. Bulk modulus
Answer : C

3. In order to have a connecting rod equally strong in buckling about X-axis and Y-axis, the moment of inertia about X-axis should be __________ the moment of inertia about Y-axis.
A. Equal to
B. Twice
C. Three times
D. Four times
Answer : D

4. The width of the pulley should be __________ width of the belt.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : C

5. 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 : B

6. A column is known as a long column if the slenderness ratio is
A. 40
B. 50
C. 70
D. 100
Answer : D

7. The taper on cotter varies from
A. 1 in 24 to 1 in 20
B. 1 in 15 to 1 in 10
C. 1 in 32 to 1 in 24
D. 1 in 48 to 1 in 24
Answer : D

8. 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.
A. Twice
B. Four times
C. Eight times
D. Sixteen times
Answer : C

9. Resilience of a material is important, when it is subjected to
A. Combined loading
B. Fatigue
C. Thermal stresses
D. Shock loading
Answer : D

10. According to I.B.R., when the thickness of boiler shell (t) is greater than 8 mm, then the diameter of rivet hole (d) is obtained by
A. Equating tearing resistance of the plate to the shearing resistance of the rivets
B. Equating tearing resistance of the plate to the crushing resistance of the rivets
C. Equating shearing resistance to the crushing resistance of the rivets
D. None of the above
Answer : B

11. In the levers of first type, the mechanical advantage is __________ one.
A. Less than
B. Equal to
C. More than
D. None of these
Answer : C

12. 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
Answer : B

13. A connecting rod is designed as a
A. Long column
B. Short column
C. Strut
D. All of these
Answer : C

14. In helical gears, the distance parallel to the axis, between similar faces of adjacent teeth, is called
A. Normal pitch
B. Axial pitch
C. Diametral pitch
D. Module
Answer : B

15. If a shaft made from ductile material is subjected to combined bending and twisting moment, calculations based on which one of the following failure theories will give the most conservative value?
A. Maximum principal stress theory
B. Maximum shear stress theory
C. Maximum strain energy theory
D. Maximum distortion energy theory
Answer : A

16. When a belt drive is transmitting maximum power,
A. Effective tension is equal to centrifugal tension
B. Effective tension is half of centrifugal tension
C. Driving tension on slack side is equal to centrifugal tension
D. Driving tension on tight side is twice the centrifugal tension
Answer : D

17. A V-belt designated as B 4430 LP has
A. 4430 mm as diameter of small pulley
B. 4430 mm as nominal pitch length
C. 4430 mm as diameter of large pulley
D. 4430 mm as centre distance between pulleys
Answer : B

18. 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 : C

19. Auto frettage is the method of
A. Joining thick cylinders
B. Calculating stresses in thick cylinders
C. Pre-stressing thick cylinders
D. Increasing the life of thick cylinders
Answer : C

20. The flank of the tooth is the
A. Surface of the top of the tooth
B. Surface of the tooth above the pitch surface
C. Width of the tooth measured along the pitch circle
D. Surface of the tooth below the pitch surface
Answer : D

21. 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 : D

22. When a closely coiled helical spring is subjected to a couple about its axis, the stress induced in the wire material of the spring is
A. Bending stress only
B. A combination of torsional shear stress and bending
C. Direct shear stress only
D. A combination of bending stress and direct shear stress
Answer : A

23. The pipe joint mostly used for pipes carrying water at low pressures is
A. Socket joint
B. Nipple joint
C. Union joint
D. Spigot and socket joint
Answer : A

24. The suitable material for belt used in flour mill is
A. Leather
B. Rubber
C. Canvas or cotton duck
D. Balata gum
Answer : C

25. 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
Answer : A

26. Soderberg relation is based on __________ of the material whereas all other failure relation for dynamic loading are based on ultimate strength of the material.
A. Elastic strength
B. Yield strength
C. Shear strength
D. None of these
Answer : B

27. According to I.B.R., the efficiency of a triple riveted butt joint with double straps of unequal width (5 rivets per pitch length) should be
A. 45 to 60 %
B. 63 to 70 %
C. 70 to 83 %
D. 80 to 90 %
Answer : D

28. The dedendum circle diameter is equal to (where ? = Pressure angle)
A. Pitch circle diameter × cos?
B. Addendum circle diameter × cos?
C. Clearance circle diameter × cos?
D. Pitch circle diameter × sin?
Answer : A

29. The washer is generally specified by its
A. Outer diameter
B. Hole diameter
C. Thickness
D. Mean diameter
Answer : B

30. 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 fibre 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
Answer : B

31. In designing a flange coupling, the pitch circle diameter of bolts is taken as (where d = Diameter of the shaft)
A. 2d
B. 3d
C. 4d
D. 5d
Answer : B

32. 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
Answer : C

33. Rankine's theory is used for
A. Brittle materials
B. Ductile materials
C. Elastic materials
D. Plastic materials
Answer : A

34. A double strap butt joint (with equal straps) is
A. Always in single shear
B. Always in double shear
C. Either in single shear or double shear
D. Any one of these
Answer : B

35. If T? and T? are the tensions on the tight and slack sides of the belt respectively, and Tc is the centrifugal tension, then initial tension in the belt is equal to
A. T? - T? + Tc
B. T? + T? + Tc
C. (T? - T? + Tc)/2
D. (T? + T? + Tc)/2
Answer : D

36. In a boundary lubricated bearing, there is a __________ of lubricant between the journal and the bearing.
A. Thick film
B. Thin film
C. Either A or B
D. None of these
Answer : B

37. In testing a material for endurance strength, it is subjected to
A. Static load
B. Dynamic load
C. Impact load
D. Completely reversed load
Answer : D

38. The metal suitable for bearings subjected to heavy loads is
A. White metal
B. Silicon bronze
C. Monel metal
D. Phosphor bronze
Answer : A

39. The power transmitted by belt drive depends upon
A. Belt velocity
B. Initial belt tension
C. Arc of contact
D. All of the above
Answer : D

40. During hot working of metals,
A. Porosity of the metal is largely eliminated
B. Grain structure of the metal is refined
C. Mechanical properties are improved due of refinement of grains
D. All of the above
Answer : D

41. The endurance limit in shear of carbon steel can be obtained by multiplying the endurance limit in flexure by a factor of
A. 0.45
B. 0.55
C. 0.65
D. 0.75
Answer : D

42. According to I.B.R., shearing resistance required to shear off the rivet per pitch length (in double shear) is (where n = Number of rivets er pitch length)
A. (?/4) d² × ? × n
B. 1.875 × (?/4) d² × ? × n
C. 2 × (?/4) d² × ? × n
D. 3 × (?/4) d² × ? × n
Answer : B

43. The process which improves the machinability of steels, but lowers the hardness and tensile strength is
A. Normalising
B. Full annealing
C. Process annealing
D. Spheroidising
Answer : D

44. Eulers formula for a mild steel column is not valid if the slenderness ratio is
A. 90
B. 60
C. 120
D. 100
Answer : B

45. The valve rod in a steam engine is connected to an eccentric rod by
A. Cotter joint
B. Bolted joint
C. Knuckle joint
D. Universal coupling
Answer : C

46. In a flange coupling, the bolts are subjected to
A. Tensile stress
B. Compressive stress
C. Shear stress
D. None of these
Answer : C

47. Wahl's stress factor __________ very rapidly as the spring index decreases.
A. Increases
B. Decreases
C. Remain same
D. None of these
Answer : A

48. According to Rankine's theory, the failure occurs at a point in a member
A. When the maximum shear stress in a biaxial stress system reaches the shear stress at elastic limit in a simple tension test
B. When the maximum principal stress in a biaxial stress system reaches the elastic limit of the material in a simple tension test
C. When the strain energy per unit volume in a biaxial stress system reaches the strain energy at the elastic limit per unit volume as determined from a simple tension test
D. When the maximum principal strain in a biaxial stress system reaches the strain at the elastic limit as determined from a simple tension test
Answer : B

49. The design of the pressure vessel is based on
A. Longitudinal stress
B. Hoop stress
C. Longitudinal and hoop stress
D. None of these
Answer : B

50. In a belt drive, if the pulley diameter is doubled keeping the tension and belt width constant, then it will be necessary to
A. Increase the key length
B. Increase the key depth
C. Increase the key width
D. Decrease the key length
Answer : A