1000+ Machine Design Multiple Choice Question Answer [Solved]

1. For a shaft diameter of 200 mm, the number of bolts in a marine flange coupling should be
A. 8
B. 6
C. 4
D. 10
Answer : A

2. 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

3. Resistance to fatigue of a material is measured by
A. Young's modulus
B. Coefficient of elasticity
C. Elastic limit
D. Endurance limit
Answer : D

4. 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. Angular bevel gears
B. Mitre gears
C. Internal bevel gears
D. Crown bevel gears
Answer : D

5. The velocity factor for precision metallic gears cut with high accuracy and operating at velocities upto 20 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 : A

6. The included angle in unified of American National threads is
A. 60°
B. 55°
C. 47°
D. 29°
Answer : A

7. In order to permit the thermal expansion/contraction of tubing, it should be
A. Crimped
B. Honed
C. Flared
D. Bent
Answer : D

8. In V-belt drive, belt touches
A. At bottom
B. At sides only
C. Both at bottom and sides
D. Could touch anywhere
Answer : B

9. The draw of cotter should not be more than
A. 3 mm
B. 6 mm
C. 8 mm
D. 12 mm
Answer : A

10. The centrifugal tension in belts
A. Decreases the power transmitted
B. Increases the power transmitted
C. Increase the wrap angle
D. Increases the belt tension without increasing power transmission
Answer : D

11. The shearing stresses in the inner face as compared to outer face of the wire in a heavy close coiled spring is
A. Larger
B. Smaller
C. Equal
D. Larger/smaller depending on diameter of spring coil
Answer : A

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

13. 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

14. In the calculation of induced shear stress in helical springs, the Wahl's stress factor is used to take care of
A. Combined effect of transverse shear stress and bending stress in the wire
B. Combined effect of bending stress and curvature of the wire
C. Combined effect of transverse shear stress and curvature of wire
D. Combined effect of torsional shear stress and transverse shear stress in the wire
Answer : B

15. The building up of worn and undersized parts, subjected to repeated loads by electroplating is
A. Best method
B. Extremely hazardous
C. Has no effect as regards fatigue strength
D. Cheapest method
Answer : A

16. In order to remove internal stresses produced by hardening the steel, the process usually adopted is
A. Tempering
B. Normalising
C. Annealing
D. Spheroidising
Answer : A

17. In cross or regular lay ropes
A. Direction of twist of wires in strands is opposite to the direction of twist of strands
B. Direction of twist of wires and strands are same
C. Wires in two adjacent strands are twisted in opposite direction
D. Wires are not twisted
Answer : A

18. 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

19. When the shaft rotates in anticlockwise direction at slow speed in a bearing, it will
A. Have contact at the bottom most of the bearing
B. Move towards right of the bearing making no metal to metal contact
C. Move towards right of the bearing making the metal to metal contact
D. Move towards left of the bearing making metal to metal contact
Answer : D

20. 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

21. The deflection of a cantilever beam under load W is 8. If its width is halved, then the deflection under load W will be
A. 2/8
B. 8/2
C. 4/8
D. 8/4
Answer : C

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

23. Which of the following is not correct procedure to increase the fatigue limit?
A. Cold working
B. Shot peening
C. Surface decarburisation
D. Under stressing
Answer : C

24. The maximum bending stress in a curved beam having symmetrical section always occur at the
A. Centroidal axis
B. Neutral axis
C. Inside fibre
D. Outside fibre
Answer : C

25. 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

26. A screw is said to be a self locking screw, if its efficiency is
A. Less than 50 %
B. More than 50 %
C. Equal to 50 %
D. None of these
Answer : A

27. 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

28. A sliding bearing which operates without any lubricant present, is called
A. Zero film bearing
B. Boundary lubricated bearing
C. Hydrodynamic lubricated bearing
D. Hydrostatic lubricated bearing
Answer : A

29. 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

30. Two shafts will have equal strength, if
A. Diameter of both the shafts is same
B. Angle of twist of both the shafts is same
C. Material of both the shafts is same
D. Twisting moment of both the shafts is same
Answer : D

31. Silver based solder is used for
A. Flaring
B. Brazing
C. Soft soldering
D. Fusion welding
Answer : B

32. For high speed engines, the cam follower should move with
A. Uniform velocity
B. Simple harmonic motion
C. Uniform acceleration and retardation
D. Cycloidal motion
Answer : D

33. When carbon in the cast iron is principally in the form of graphite, the cast iron will be of
A. Brown colour
B. Yellow colour
C. White colour
D. Grey colour
Answer : D

34. 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

35. The elasticity is the property of a material which enables it to
A. Regains its original shape after deformation when the external forces are removed
B. Draw into wires by the application of a tensile force
C. Resists fracture due to high impact loads
D. Retain deformation produced under load permanently
Answer : A

36. The effective stress in wire ropes during normal working is equal to the stress due to
A. Axial load plus stress due to bending
B. Acceleration/retardation of masses plus stress due to bending
C. Axial load plus stress due to acceleration/retardation
D. Bending plus stress due to acceleration/retardation
Answer : A

37. Transverse fillet welded joints are designed for
A. Tensile strength
B. Compressive strength
C. Shear strength
D. Bending strength
Answer : A

38. The stretching in a belt can be controlled by __________ the stress in the belt.
A. Reducing
B. Increasing
C. Both A and B
D. None of these
Answer : A

39. 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

40. A key made from a cylindrical disc having segmental cross-section, is known as
A. Woodruff key
B. Feather key
C. Flat saddle key
D. Gib head key
Answer : A

41. 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

42. 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?
Anser : A

43. The radial distance of a tooth from the pitch circle to the top of the tooth is called
A. Addendum
B. Dedendum
C. Clearance
D. Working depth
Answer : A

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

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

46. According to Unwin's formula, the relation between the diameter of rivet hole (d) and the thickness of plate (t) is given by (where d and t are in mm)
A. d = t
B. d = 1.6 t
C. d = 2t
D. d = 6t
Answer : D

47. For a square key made of mild steel, the shear and crushing strength are related as
A. Shear strength is equal to crushing strength
B. Shear strength is greater than crushing strength
C. Shear strength is less than crushing strength
D. None of the above
Answer : A

48. The included angle between the sides of V-belt is
A. 40°
B. 45°
C. 38°
D. 60°
Answer : A

49. The lower deviation is the algebraic difference between the
A. Actual size and the corresponding basic size
B. Maximum limit and the basic size
C. Minimum limit and the basic size
D. None of the above
Answer : C

50. 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