1000+ Machine Design Multiple Choice Question Answer [Solved]

1. 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

2. Which of the following key is preferred for the condition when a large amount of impact type torque is to be transmitted in both direction of rotation?
A. Woodruff key
B. Feather key
C. Gib-head key
D. Tangent key
Answer : D

3. The connecting rod bolts are tightened up so that tightening stress
A. Is just sufficient to hold parts together
B. Approaches yield point
C. Is 50% of yield point
D. Is about yield point divided by safety factor
Answer : B

4. The standard length of the shaft is
A. 6 m
B. 5 m
C. 7 m
D. All of these
Answer : D

5. Two closely coiled helical springs with stiffness k? and k? respectively are connected in series. The stiffness of an equivalent spring is given by
A. (k? k?)/ (k? + k?)
B. (k? - k?)/ (k? + k?)
C. (k? + k?)/ (k? k?)
D. (k? - k?)/ (k? k?)
Answer : A

6. When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be
A. Knuckle threads
B. Square threads
C. Acme threads
D. Buttress threads
Answer : D

7. A shaft is subjected to fluctuating loads for which the normal torque (T) and bending moment (M) are 1000 N-m and 500 N-m respectively. If the combined shock and fatigue factor for bending is 1.5 and combined shock and fatigue factor for torsion is 2, then the equivalent twisting moment for the shaft is
A. 2000 N-m
B. 2050 N-m
C. 2100 N-m
D. 2136 N-m
Answer : D

8. When a helical compression spring is cut into halves, the stiffness of the resulting spring will be
A. Same
B. Double
C. One-half
D. One-fourth
Answer : B

9. In radial cams, the follower moves
A. In a direction parallel to the cam axis
B. In a direction perpendicular to the cam axis
C. In any direction irrespective of cam axis
D. Along the cam axis
Answer : B

10. According to Indian standard specifications, 100 H6/g5 means that
A. Tolerance grade for the hole is 6 and for the shaft is 5
B. Tolerance grade for the shaft is 6 and for the hole is 5
C. Tolerance grade for the shaft is 4 to 8 and for the hole is 3 to 7
D. Tolerance grade for the hole is 4 to 8 and for the shaft is 3 to 7
Answer : A

11. The cracks in helical springs used in railway carriages usually start on the inner side of the coil because of the fact that
A. It is subjected to a higher cyclic loading than the outer side
B. It is subjected to a higher stress than the outer side
C. It is more stretched than the outer side during the manufacturing process
D. It has a lower curvature than the outer side
Answer : A

12. The maximum shear stress theory is used for
A. Brittle materials
B. Ductile materials
C. Plastic materials
D. Nonferrous materials
Answer : B

13. 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

14. A stud
A. Has a head on one end and a nut fitted to the other
B. Has head at one end and other end fits into a tapped hole in the other part to be joined
C. Has both the ends threaded
D. Has pointed threads
Answer : C

15. The ratio of endurance limit in shear to the endurance limit in flexure is
A. 0.70
B. 0.25
C. 0.40
D. 0.55
Answer : D

16. Rankine Gordon formula for buckling is valid for
A. Long column
B. Short column
C. Short and long column
D. Very long column
Answer : C

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

18. 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

19. The objective of idler pulley in belt drive is to
A. Decrease the tendency of belt to slip
B. Increase the power transmission capacity
C. Increase the wrap angle and belt tension
D. All the above objectives
Answer : D

20. 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

22. Set 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. Similar to stud
Answer : C

23. The spring mostly used in gramophones is
A. Helical spring
B. Conical spring
C. Flat spiral spring
D. Volute spring
Answer : C

24. 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

25. Which of the following is a permanent fastening?
A. Bolts
B. Keys
C. Cotters
D. Rivets
Answer : D

26. In hydrodynamic 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 : A

27. 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

28. The endurance or fatigue limit is defined as the maximum value of the stress which a polished standard specimen can withstand without failure, for infinite number of cycles, when subjected to
A. Static load
B. Dynamic load
C. Static as well as dynamic load
D. Completely reversed load
Answer : D

29. The velocity factor for ordinary cut gears operating at velocities upto 12.5 m/s is equal to
A. 0.75/ (0.75 + ?v)
B. 3/ (3 + v)
C. 4.5/ (4.5 + v)
D. 6/ (6 + v)
Answer : B

30. An Involute pinion and gear are in mesh. If both have the same size of addendum, then there will be interference between the
A. Tip of the pinion and flank of gear
B. Tip of the gear and flank of pinion
C. Flanks of both gear and pinion
D. Tip of both gear and pinion
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. The stress in the threaded part of the bolt will be __________ as compared to the shank.
A. Same
B. Higher
C. Lower
D. None of these
Answer : B

33. The velocity factor for very accurately cut and ground metallic gears operating at velocities upto __________ are equal to 6/(6 + v).
A. 10 m/s
B. 12.5 m/s
C. 15 m/s
D. 20 m/s
Answer : D

34. 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

35. Maximum principal stress theory is applicable for
A. Ductile materials
B. Brittle materials
C. Elastic materials
D. All of the above
Answer : B

36. In second type of levers,
A. Load is in between the fulcrum and effort
B. Effort is in between the fulcrum and load
C. Fulcrum is in between the load and effort
D. None of these
Answer : A

37. When bevel gears having equal teeth and equal pitch angles connect two shafts whose axes intersect at right angle, then they are known as
A. Angular bevel gears
B. Crown bevel gears
C. Internal bevel gears
D. Mitre gears
Answer : D

38. The draw of cotter need not exceed
A. 3 mm
B. 5 mm
C. 10 mm
D. 20 mm
Answer : A

39. Which of the following screw thread is used for power transmission in one direction only?
A. Square threads
B. Multiple threads
C. Acme threads
D. Buttress threads
Answer : D

40. The included angle for the British Association thread is
A. 29°
B. 55°
C. 47.3°
D. 60°
Answer : B

41. The connecting rod bolts are tightened up with initial tension greater than the external load so that
A. Joint may not open up
B. Bolts are weakest elements
C. The resultant load on the bolt would not be affected by the external cyclic load
D. Bolts will not loosen during service
Answer : C

42. The fatigue stress concentration factor is defined as
A. The ratio of endurance limit with stress concentration to the endurance limit without stress concentration
B. The ratio of endurance limit without stress concentration to the endurance limit with stress concentration
C. The product of the endurance limits with and without stress concentation
D. All of the above
Answer : B

43. Ball bearing type screws are found in following application
A. Screw jack
B. Aeroplane engines
C. Crane
D. Steering mechanism
Answer : D

44. The notch angle of the Izod impact test specimen is
A. 10°
B. 20°
C. 30°
D. 45°
Answer : D

45. 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

46. When bevel gears connect two shafts whose axes intersect at an angle greater than a right angle and one of the bevel gears has a pitch angle of 90°, then they are known as
A. Crown bevel gears
B. Angular bevel gears
C. Mitre gears
D. Internal bevel gears
Answer : A

47. Which of the following statement is wrong for a connecting rod?
A. The connecting rod will be equally strong in buckling about X-axis and Y-axis, if I_xx = 4 I_yy
B. If I_xx > 4 I_yy, the buckling will occur about Y-axis
C. If I_xx < 4 I_yy, the buckling will occur about X-axis
D. The most suitable section for the connecting rod is T-section
Answer : D

48. The temperature required for full annealing in hypereutectoid steel is
A. 50°C above upper critical temperature
B. 50°C below upper critical temperature
C. 50°C above lower critical temperature
D. 50°C below lower critical temperature
Answer : A

49. A single strap butt joint is always in __________ shear.
A. Single
B. Double
C. Triple share
D. None of these
Answer : A

50. The usual clearance provided in hydrodynamic bearing per mm of diameter of shaft is
A. 0.01 micron
B. 0.1 micron
C. 1 micron
D. 10 microns
Answer : C