Mechanical Engineering - MCQ Practice Questions
Core mechanical MCQs — thermodynamics, SOM, fluid mechanics for GATE & PSUs.
259 questions | 100% Free
A heat engine operating between two temperature reservoirs has a maximum theoretical efficiency given by:
In a throttling process (Joule-Thomson expansion), the enthalpy of the fluid:
The availability or exergy of a system is zero when the system is in:
For a real gas, the compressibility factor Z is defined as:
The polytropic process for an ideal gas follows PV^n = constant. When n = 0, the process is:
In a closed system, the total energy balance equation for a time interval is:
Two bodies at different temperatures are brought into contact in an isolated system. The total entropy of the system will:
The specific heat capacity at constant volume (Cv) for a monatomic ideal gas is:
In a vapour compression refrigeration cycle, the throttling device (expansion valve) causes:
A piston-cylinder device contains 0.5 kg of steam at 200°C. Heat is removed and the steam condenses to saturated liquid at the same temperature. The latent heat of vaporization at 200°C is 1941 kJ/kg. Calculate heat removed.
In the Rankine cycle, which process involves expansion in a turbine?
Which of the following processes is impossible according to the second law of thermodynamics?
What is the dryness fraction (quality) of steam at a state where internal energy u = 2400 kJ/kg, u_f = 1317.3 kJ/kg, and u_fg = 1753.7 kJ/kg?
In a polytropic process PV^n = constant, if n = 1, the process is:
In an Otto cycle, the compression ratio is 10 and γ = 1.4. Calculate the thermal efficiency.
At what condition is the specific heat capacity at constant pressure equal to infinity?
A heat engine receives 2000 J from a hot reservoir and rejects 1200 J to a cold reservoir. What is the thermal efficiency and work output?
A reversible heat engine operates between two thermal reservoirs. If the temperature of the hot reservoir is 500 K and the cold reservoir is 300 K, what is the maximum possible efficiency of this engine?
Which of the following statements is correct regarding the first law of thermodynamics?
During an adiabatic expansion of an ideal gas, the temperature of the gas decreases. This is because: