1000+ Machine Design Multiple Choice Question Answer [Solved]

1. Stress concentration in static loading is more serious in
A. Ductile materials
B. Brittle materials
C. Equally serious in both cases
D. Depends on other factors
Answer : B

2. The shear stress at a point in a shaft subjected to a torque is
A. Directly proportional to the polar moment of inertia and to the distance of the point from the axis
B. Directly proportional to the applied torque and inversely proportional to the polar moment of inertia
C. Directly proportional to the applied torque and the polar moment of inertia
D. Inversely proportional to the applied torque and the polar moment of inertia
Answer : B

3. 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

4. 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

5. The bending moment M and a torque T is applied on a solid circular shaft. If the maximum bending stress equals to maximum shear stress developed, then M is equal to
A. T/2
B. T
C. 2T
D. 4T
Answer : A

6. 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

7. In order to ensure self locking in a screw jack, it is essential that helix angle is __________ friction angle.
A. Larger than
B. Smaller than
C. Equal to
D. None of these
Answer : B

8. 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

9. 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

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

11. 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

12. 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

13. In replacing the V-belts, a complete set of new belts is used instead of replacing a single damaged belt because
A. Belts are available in sets
B. Only one belt cannot be fitted with other used belts
C. The new belt will carry more than its share and result in short life
D. New and old belts will cause vibrations
Answer : C

14. The form factor of a helical gear __________ with the increase in the helix angle.
A. Increases
B. Decreases
C. Remains constant
D. None of these
Answer : A

15. 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 : A

16. 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

17. The maximum efficiency of a square threaded screw is
A. (1 - sin?)/ (1 + sin?)
B. (1 + sin?)/ (1 - sin?)
C. (1 - sin?)/ (1 + cos?)
D. (1 + cos?)/ (1 - sin?)
Answer : A

18. 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

19. A screw is said to be over hauling screw, if its efficiency is
A. More than 50 %
B. Less than 50 %
C. Eqal to 50 %
D. None of these
Answer : A

20. The resilience of a bolt may be increased by
A. Increasing its shank diameter
B. Increasing its length
C. Decreasing its shank diameter
D. Decreasing its length
Answer : B

21. 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

22. The coefficient of friction in belt drive depends upon
A. Material of belt
B. Material of pulley
C. Materials of belt and pulley
D. Belt velocity
Answer : C

23. 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

24. Stress concentration is caused due to
A. Variation in properties of material from point to point in a member
B. Pitting at points or areas at which loads on a member are applied
C. Abrupt change of section
D. All of the above
Answer : D

25. 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

26. 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

27. In order to avoid tearing of the plate at an edge, the distance from the centre line of the rivet hole to the nearest edge of the plate should be equal to (where d = Diameter of rivet hole)
A. d
B. 1.5 d
C. 2.5 d
D. 2 d
Answer : B

28. The ratio of pitch circle diameter in millimetres to the number of teeth, is called
A. Circular pitch
B. Diametral pitch
C. Module
D. None of these
Answer : C

29. A circular shaft can transmit a torque of 5 kN-m. If the torque is reduced to 4 kN-m, then the maximum value of bending moment that can be applied to the shaft is
A. 1 kN-m
B. 2 kN-m
C. 3 kN-m
D. 4 kN-m
Answer : C

30. Factor of safety for fatigue loading is the ratio of
A. Elastic limit to the working stress
B. Elastic limit to the yield point
C. Endurance limit to the working stress
D. Young's modulus to the ultimate tensile strength
Answer : C

31. The relation between the pitch of the chain (p) and pitch circle diameter of the sprocket (D) is given by (where T = Number of teeth on the sprocket)
A. p = D sin (90°/T)
B. p = D sin (120°/T)
C. p = D sin (180°/T)
D. p = D sin (360°/T)
Answer : C

32. 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

33. A bolt
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. Is provided with pointed threads
Answer : A

34. A flange coupling is used to connect two shafts
A. Which are perfectly aligned
B. Which are not in exact alignment
C. Have lateral misalignment
D. Whose axes intersect at a small angle
Answer : A

35. A localised compressive stress at the area of contact between two members is known as
A. Tensile stress
B. Bending stress
C. Bearing stress
D. Shear stress
Answer : C

36. 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

37. The ultimate strength of steel in tension in comparison to shear is in the ratio of
A. 1 : 1
B. 2 : 1
C. 3 : 2
D. 2 : 3
Answer : C

38. A feather key is generally
A. Loose in shaft and tight in hub
B. Tight in shaft and loose in hub
C. Tight in both shaft and hub
D. Loose in both shaft and hub
Answer : B

39. The edges of a boiler plate are bevelled to an angle of
A. 30°
B. 45°
C. 60°
D. 80°
Answer : D

40. The acme threads are usually found on
A. Spindles of bench vices
B. Railway carriage couplings
C. Feed mechanism of machine tools
D. Screw cutting lathes
Answer : D

41. A column of length l is fixed at both ends. The equivalent length of the column is
A. l/2
B. l/?2
C. l
D. 2 l
Answer : A

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

43. A sliding bearing which can support steady loads without any relative motion between the journal and the bearing, is called
A. Hydrostatic lubricated bearing
B. Hydrodynamic lubricated bearing
C. Boundary lubricated bearing
D. Zero film bearing
Answer : A

44. The design of pin of a rocker arm of an I.C. engine is based on
A. Bearing failure
B. Shearing failure
C. Bending failure
D. All of these
Answer : D

45. When two nonintersecting and non-coplanar shafts are connected by gears, the arrangement is known as
A. Spur gearing
B. Helical gearing
C. Bevel gearing
D. Spiral gearing
Answer : D

46. The most important dimension in the design of a nut is
A. Pitch diameter
B. Inside diameter
C. Outside diameter
D. Height
Answer : D

47. According to I.B.R., the distance between the rows of rivets, for equal number of rivets in more than one row for lap joint or butt joint (chain riveting) shall not be less than
A. d
B. 1.5 d
C. 2d
D. 2.5 d
Answer : C

48. Taper usually provided on cotter is
A. 1 in 5
B. 1 in 10
C. 1 in 24
D. 1 in 40
Answer : C

49. A locking device extensively used in marine type connecting rod ends is a
A. Jam nut
B. Castle nut
C. Sawn nut
D. Ring nut
Answer : D

50. 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