Mechanical Engineering MCQs
Mechanical Engineering MCQs are a crucial resource for students and job seekers preparing for competitive tests in Pakistan. This section features MCQs from all major areas including thermodynamics, fluid mechanics, machine design, manufacturing processes, engineering materials, and mechanics of solids. These questions are crafted to meet the standards of exams like PPSC, FPSC, NTS, and university entry or semester tests. Each MCQ is aimed at testing your fundamental understanding and problem-solving ability, making them perfect for both fresh graduates and experienced professionals. With a wide range of topics, this category ensures a comprehensive practice session for anyone looking to ace Mechanical Engineering exams.
Q: Internal energy of a system increases when heat is added at constant volume
A) No temperature change
B) All the above
C) Work done by system
D) No heat transfer
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Correct Answer: D
Explanation: At constant volume, no work is done, so heat increases internal energy.
Q: Steam turbines are preferred over gas turbines for
A) High initial cost
B) Constant load conditions
C) Low pressure application
D) Quick start-up
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Correct Answer: B
Explanation: Steam turbines are ideal for steady, base-load conditions due to efficiency.
Q: The ratio of specific heats (ฮณ = Cp/Cv) for air is nearly
A) 1.0
B) 1.4
C) 1.33
D) 1.67
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Correct Answer: B
Explanation: For diatomic gases like air, ฮณ is typically 1.4.
Q: Rankine cycle efficiency increases when
A) Boiler pressure is reduced
B) Condenser pressure is increased
C) Superheating is done
D) Feedwater is cooled
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Correct Answer: C
Explanation: Superheating improves thermal efficiency by reducing moisture in turbine exhaust.
Q: Hardness of a material is its ability to
A) Resist deformation
B) Resist wear and abrasion
C) Break easily
D) Withstand impact
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Correct Answer: B
Explanation: Hardness measures a material's resistance to surface indentation and abrasion.
Q: When two gears are meshed, the smaller is called
A) Driver
B) Pinion
C) Rack
D) Sprocket
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Correct Answer: B
Explanation: The smaller of two meshed gears is the pinion.
Q: Otto cycle is used in
A) Steam turbines
B) Diesel engines
C) Jet engines
D) Gasoline engines
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Correct Answer: D
Explanation: The Otto cycle represents the ideal cycle for spark ignition (gasoline) engines.
Q: Materials are tempered after hardening to
A) Increase hardness
B) Improve elasticity
C) Induce stress
D) Reduce brittleness
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Correct Answer: D
Explanation: Tempering reduces brittleness while maintaining strength.
Q: The efficiency of a Carnot engine depends on
A) Working fluid
B) Pressure ratio
C) Temperature difference
D) Volume ratio
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Correct Answer: C
Explanation: Carnot efficiency depends only on source and sink temperatures.
Q: The Reynolds number is used to predict
A) Fluid density
B) Flow regime
C) Heat transfer
D) Pipe diameter
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Correct Answer: B
Explanation: Reynolds number determines whether the flow is laminar or turbulent.