Mechanical Engineering MCQs
Mechanical Engineering MCQs for competitive exams in Pakistan cover thermodynamics, fluid mechanics, machine design, manufacturing, and materials. Ideal for PPSC, FPSC, NTS, and university tests, they help students and professionals enhance concepts and problem-solving skills.
Q: When two gears are meshed, the smaller is called
A) Driver
B) Pinion
C) Rack
D) Sprocket
✅ 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
✅ 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
✅ 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
✅ 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
✅ Correct Answer: B
Explanation: Reynolds number determines whether the flow is laminar or turbulent.