Machine Design MCQ Questions & Answers

71

Two shafts of the same length and material are joined in series. If the ratio of their diameters is 2, then the ratio of their angles of twist will be

A) 2 B) 4 C) 8 D) 16

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Answer & Solution

Answer: Option D

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72

In oilness 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 required to be applied after some intervals

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Answer & Solution

Answer: Option C

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73

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) $${\text{p}} = {\text{D}}\sin \frac{{{{90}^ \circ }}}{{\text{T}}}$$ B) $${\text{p}} = {\text{D}}\sin \frac{{{{120}^ \circ }}}{{\text{T}}}$$ C) $${\text{p}} = {\text{D}}\sin \frac{{{{180}^ \circ }}}{{\text{T}}}$$ D) $${\text{p}} = {\text{D}}\sin \frac{{{{360}^ \circ }}}{{\text{T}}}$$

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Answer & Solution

Answer: Option C

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74

In standard taper roller bearings, the angle of taper of outer raceway is

A) 5° B) 8° C) 15° D) 25°

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Answer & Solution

Answer: Option D

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75

In case of pressure vessels having open ends, the fluid pressure induces

A) Longitudinal stress B) Circumferential stress C) Shear stress D) None of these

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Answer & Solution

Answer: Option B

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76

In case of pressure vessels having closed ends, the fluid pressure induces

A) Longitudinal stress B) Shear stress C) Circumferential stress D) None of these

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Answer & Solution

Answer: Option A

Solution:

Closed-end pressure vessels experience additional forces due to internal fluid pressure acting on the end caps.

Circumferential (hoop) stress acts around the circumference and tends to increase the diameter of the vessel. This is always present in thin-walled cylinders.

Longitudinal stress arises only when the vessel has closed ends, because the fluid pressure pushes on the end surfaces. This force tries to pull the ends apart, creating stress along the length of the vessel.

Shear stress does not play a significant role in such cases.

Conclusion: In pressure vessels with closed ends, the internal fluid pressure induces a longitudinal stress in addition to hoop stress, and the correct answer here is longitudinal stress.

77

A saddle key __________ power through frictional resistance only.

A) Transmits B) Does not transmit C) Either A or B D) None of these

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Answer & Solution

Answer: Option A

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78

The endurance limit of a material with finished surface in comparison to rough surface is

A) More B) Less C) Same D) More or less depending on quantum of load

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Answer & Solution

Answer: Option A

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79

A locking device in which the bottom cylindrical portion is recessed to receive the tip of the locking set screw, is called

A) Ring nut B) Castle nut C) Sawn nut D) Jam nut

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Answer & Solution

Answer: Option A

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80

A screw will be self locking, if

A) Friction angle is less than helix angle B) Friction angle is more than helix angle C) Friction angle is equal to helix angle D) Efficiency of screw is 100%

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Answer & Solution

Answer: Option B

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Machine Design MCQ Questions & Answers | Mechanical Engineering