1000+ Machine Design MCQ for NEET PG [Solved]

1. The smallest diameter of an external or internal screw thread is known as
A. Minor diameter
B. Major diameter
C. Pitch diameter
D. None of these
Answer : A

2. In levers, leverage is the ratio of
A. Load lifted to the effort applied
B. Mechanical advantage to the velocity ratio
C. Load arm to the effort arm
D. Effort arm to the load arm
Answer : D

3. 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

4. The circumferential and longitudinal strains in a cylindrical boiler under internal steam pressure are ?c and ?l respectively. The change in volume of the boiler cylinder per unit volume will be
A. ?_c + 2?_l
B. 2?_c + ?_l
C. ?_c + ?_l²
D. ?_c² + ?_l
Answer : B

5. 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 : D

6. The gears are termed as medium velocity gears, if their peripheral velocity is
A. 1-3 m/s
B. 3-15 m/s
C. 15-30 m/s
D. 30-50 m/s
Answer : B

7. 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

8. The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
A. 12
B. 14
C. 18
D. 24
Answer : C

9. If a load W is applied instantaneously on a bar; Then the stress induced in bar will
A. Be independent of ratio of mass of load W to mass of bar (y)
B. Increase with increase in y
C. Decrease with decrease in y
D. Depend on other considerations
Answer : A

10. In designing a connecting rod, it is considered like __________ for buckling about X-axis.
A. Both ends hinged
B. Both ends fixed
C. One end fixed and the other end hinged
D. One end fixed and the other end free
Answer : A

11. The tension on the slack side of the belt is __________ the tension on the tight side of the belt.
A. Equal to
B. Less than
C. Greater than
D. None of these
Answer : B

12. The stiffness of a closely coiled helical spring subjected to an axial load W is equal to (where G = Modulus of rigidity, and n = Number of active coils)
A. Gd?/ 8D³n
B. Gd³/ 8D³n
C. Gd?/ 4D³n
D. Gd?/ 8D²n
Answer : A

13. When compared to the rod of the same diameter and material, a wire rope
A. Is less flexible
B. Has a much smaller load carrying capacity
C. Does not provide much warning before failure
D. Provides much greater time for remedial action before failure
Answer : B

14. 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

15. For a shaft diameter of 100 mm, the number of bolts in a flange coupling should be
A. 4
B. 6
C. 8
D. 10
Answer : A

16. Yield point in fatigue loading as compared to static loading is
A. Same
B. Higher
C. Lower
D. Depends on other factors
Answer : C

17. The load cup of a screw jack is made separate from the head of the spindle to
A. Prevent the rotation of load being lifted
B. Enhance the load carrying capacity of the jack
C. Reduce the effort needed for lifting the working load
D. Reduce the value of frictional torque
Answer : A

18. 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 : B

19. In hydrostatic bearings
A. The Oil film pressure is generated only by the rotation of the journal
B. The oil film is maintained by supplying oil under pressure
C. Do not require external supply of lubricant
D. Grease is used for lubrication
Answer : B

strong>20. 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 centre 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 : B

21. The notch sensitivity q is expressed in terms of fatigue stress concentration factor Kf and theoretical stress concentration factor Kt as
A. (K_f + 1)/ (K_t + 1)
B. (K_f - 1)/ (K_t - 1)
C. (K_t + 1)/ (K_f + 1)
D. (K_t - 1)/ (K_f - 1)
Answer : B

22. Multiple threads are used to secure
A. Low efficiency
B. High efficiency
C. High load lifting capacity
D. High mechanical advantage
Answer : B

23. The expression 0.175 - 0.841/T is the Lewis form factor for
A. 14 ½° composite and full depth involute system
B. 20° full depth involute system
C. 20° stub system
D. None of the above
Answer : C

24. If P1 and P2 are the tight and slack side tensions in the belt, then the initial tension Pi (neglecting centrifugal tension) will be equal to
A. P₁ - P₂
B. P₁ + P₂
C. ?2 × (P₁ + P₂)
D. [?2 × (P₁ + P₂)] + P_c Where Pc is centrifugal tension
Answer : C

25. The designation M 33 × 2 of a bolt means
A. Metric threads of 33 numbers in 2 cm
B. Metric threads with cross-section of 33 mm
C. Metric threads of 33 mm outside diameter and 2 mm pitch
D. Bolt of 33 mm nominal diameter having 2 threads per cm
Answer : C

26. In worm gears, the pressure angle is ________ the angle between two inclined faces in axial plane.
A. Half
B. Twice
C. Thrice
D. None of these
Answer : A

27. The arms of the pulleys for flat belt drive have
A. Elliptical cross-section
B. Major axis in plane of rotation
C. Major axis twice the minor axis
D. All the three characteristics
Answer : D

28. When the connected members are very yielding (soft gasket) as compared to the bolt, then the resultant load on the bolt will be equal to the
A. Initial tension
B. External load applied
C. Sum of the initial tension and external load applied
D. Initial tension or external load, whichever is greater
Answer : C

29. A bench vice has following type of threads
A. Metric
B. Square
C. Buttress
D. Acme
Answer : D

30. For longitudinal joint in boilers, the type of joint used is
A. Butt joint with single cover plate
B. Butt joint with double cover plate
C. Lap joint with one ring overlapping the other
D. Any one of the above
Answer : B

31. A key capable of tilting in a recess milled out in a shaft is known as
A. Woodruff key
B. Feather key
C. Flat saddle key
D. Hollow saddle key
Answer : A

32. A tube has the following advantage over pipe
A. Lighter and easier to handle
B. Greater shock absorption
C. Smoother inside walls
D. All of the above
Answer : D

33. Rivets are generally specified by
A. Thickness of plates to be riveted
B. Length of rivet
C. Diameter of head
D. Nominal diameter
Answer : D

34. Creep in belt is due to
A. Material of the belt
B. Material of the pulley
C. Uneven extensions and contractions due to varying tension
D. All of the above
Answer : C

35. The bearings of medium series have capacity __________ over the light series.
A. 10 to 20 %
B. 20 to 30 %
C. 30 to 40 %
D. 40 to 50 %
Answer : C

36. The included angle for the V-belt is usually
A. 10°-20°
B. 30°-40°
C. 40°-60°
D. 60°-80°
Answer : B

37. A bolt of M 24 × 2 means that
A. The pitch of the thread is 24 mm and depth is 2 mm
B. Cross-sectional area of the threads is 24 mm²
C. The nominal diameter of bolt is 24 mm and pitch is 2 mm
D. The effective diameter of bolt is 24 mm and there are 2 threads per cm
Answer : C

38. An open belt drive is used when
A. Shafts are arranged at right angles and rotate in one definite direction
B. Shafts are arranged parallel and rotate in the opposite directions
C. Shafts are arranged parallel and rotate in the same directions
D. Driven shaft is to be started or stopped whenever desired without interfering with the driving shaft
Answer : C

39. 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 ? = Stress for a plate with no hole i.e. nominal stress)
A. ? [1 + (b/2a)]
B. ? [1 + (2a/b)]
C. ? [1 + (b/3a)]
D. ? [1 + (3a/b)]
Answer : B

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

41. An imaginary circle which by pure rolling action gives the same motion as the actual gear, is called
A. Addendum circle
B. Dedendum circle
C. Pitch circle
D. Clearance circle
Answer : C

42. 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

43. 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

44. 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 : D

45. According to Indian standards, total numbers of fundamental deviations are
A. 10
B. 15
C. 20
D. 25
Answer : D

46. 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 : A

47. The contact ratio for gears is
A. Zero
B. Less than one
C. Greater than one
D. None of these
Answer : C

48. In designing a key, it is assumed that the distribution of forces along the length of key
A. Varies linearly
B. Is uniform throughout
C. Varies exponentially, being more at the torque-input end
D. Varies exponentially, being less at the torque-input end
Answer : B

49. Which of the following statement is correct?
A. The stress concentration in static loading is more serious in ductile materials and less serious in brittle materials
B. The stress concentration in static loading is more serious in brittle materials and less serious in ductile materials
C. The toughness of a material increases when it is heated
D. The shear stress in a beam varies from zero at the neutral surface and maximum at the outer fibres
Answer : B

50. The cam follower extensively used in aircraft engines is
A. Knife edge follower
B. Flat faced follower
C. Spherical faced follower
D. Roller follower
Answer : D