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Machine Design MCQ Questions & Answers | Mechanical Engineering

Learn Machine Design MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Machine Design MCQ question is the important chapter for a Mechanical Engineering and GATE students. Page-4 section-1

Each section contains 100 MCQs on Machine Design .
31
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
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Answer & Solution
Answer: Option D
No explanation is given for this question. Let's Discuss on Board
32
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
Discuss
Answer & Solution
Answer: Option D
Solution:
Buttress threads are best suited when power is transmitted in one direction only.

Reason: These threads have one face nearly perpendicular to the axis and the other face at an angle. This gives them high strength to transmit force efficiently in one direction, while reducing friction losses.

Other options:
- Knuckle threads are mainly used in couplings and linkages subjected to heavy jerks and vibrations, not for power transmission.

- Square threads are used for power transmission where efficiency is needed in both directions, such as in screw jacks and presses.

- Acme threads are easier to manufacture than square threads and are widely used in lead screws of lathes, where motion is required in both directions.

Conclusion: Therefore, buttress threads are most suitable when the load or power acts in one direction only.
33
The property of a material which enables it to be drawn into wires with the application of a tensile force, is called
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Answer & Solution
Answer: Option C
No explanation is given for this question. Let's Discuss on Board
34
The root angle of a bevel gear is equal to
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Answer & Solution
Answer: Option C
No explanation is given for this question. Let's Discuss on Board
35
The face angle of a bevel gear is equal to
Discuss
Answer & Solution
Answer: Option B
No explanation is given for this question. Let's Discuss on Board
36
The longitudinal joint in boilers is used to get the required
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Answer & Solution
Answer: Option B
No explanation is given for this question. Let's Discuss on Board
37
According to Indian standard specifications, 100 H6/g5 means that
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Answer & Solution
Answer: Option A
No explanation is given for this question. Let's Discuss on Board
38
The usual proportion for the width of key is (where d = Diameter of shaft or diameter of hole in the hub)
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Answer & Solution
Answer: Option C
No explanation is given for this question. Let's Discuss on Board
39
The suitable material for belt used in flour mill is
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Answer & Solution
Answer: Option C
No explanation is given for this question. Let's Discuss on Board
40
When a machine member is subjected to torsion, the torsional shear stress set up in the member is
Discuss
Answer & Solution
Answer: Option C
Solution:
The torsional shear stress in a circular shaft varies linearly from the centre to the outer surface of the shaft.

According to the torsion equation:

τ = (T × r) / J

Where:
τ = Torsional shear stress
T = Applied torque
r = Radial distance from the centre
J = Polar moment of inertia

Since the stress is directly proportional to the radial distance (τ ∝ r):

• At the centroidal axis (r = 0): Shear stress is zero.
• At the outer surface (r = R): Shear stress is maximum.

Therefore, the correct statement is that the torsional shear stress is zero at the centroidal axis and maximum at the outer surface of the member.