SSC, RRB JE ME Thermodynamics Previous Years Questions Download

SSC JE and RRB JE Previous Years Questions for Mechanical Engineers from the topic Thermodynamics, Heat Transfer, IC Engines Part 1

Thermodynamics, IC Engines and Heat Transfer topics have an important role in SSC Junior Engineer Exam for Mechanical Engineering Students. Out of 100 questions you can expect about 30 questions from Thermodynamics and Heat Transfer. To score this 30 marks for SSC Junior Engineer ME, you should have good knowledge in the theory part. Below given are some important questions from Thermodynamics and Heat Transfer topic, which were asked previously. By going through this previous years question you will get an idea on questions. This makes you to concentrate your preparation on certain topics.

Brief Syllabus : 1st Law of Thermodynamics, 2nd Law of Thermodynamics, Air
standard Cycles for IC Engines, IC Engine Performance, IC Engines Combustion, IC Engine
Cooling & Lubrication, Rankine cycle of System, Boilers, Classification, Specification, Fitting &
Accessories,

Even though the topic mentioned in official syllabus is very less, you can expect more questions from those topics as asked in the below questions.

• [accordion]
• 1. The ___________ is a dimensionless quantity used in heat transfer calculations.  
• A.  Grashoff number
  B.  Biot number 
  C.   Stanton number 
  D.  Prandtl number 
• Answer
• Ans. B
• Explanation

• [accordion]
• 2. An ideal air compressor cycle (with clearance) on p-v diagram can be represented by ____ processes.  
• A. one adiabatic, two isobaric, and one constant volume 
  B. two adiabatic and two isobaric 
  C. two adiabatic, one isobaric and one constant volume 
  D. one adiabatic, one isobaric and two constant volume
• Answer
• Ans. B 
• Explanation

• [accordion]
• 3. In a shell and tube heat exchanger, baffles are provided on the shell side to ________.
•  A. Prevent the stagnation of shell side fluid 
  B. Improve heat transfer 
  C. Provide support for tubes 
  D. All options are correct
• Answer
• Ans D
• Explanation

• [accordion]
• 4. The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is ________.  
• A. -1/3 
  B. -2/3 
  C. 1 
  D. -1 
• Answer
• Ans. A Sol
• Explanation

• [accordion]
• 5. In regarding nucleate boiling __________.  
• A. The temperature of the surface is greater than the saturation temperature of the liquid 
  B. Bubbles are created by expansion of entrapped gas or vapour at small cavities in the surface 
  C. The temperature is greater than that of film boiling 
  D. All options are correct
• Answer
• Ans. C
• Explanation

• [accordion]
• 6. Boundary layer is defined as __________.  
• A. A thin layer at the surface where gradients of both velocity and temperature are small 
  B. A thin layer at the surface where velocity and velocity gradients are large 
  C. A thick layer at the surface where velocity and temperature gradients are large
   D. A thin layer at the surface where gradients of both velocity and temperature are large 
• Answer
• Ans. D
• Explanation

• [accordion]
• 7. Two insulating materials of thermal conductivity K and 2K are available for lagging a pipe carrying a hot fluid. If the radial thickness of each material is the same _________.
•  A. Material with higher thermal conductivity should be sued for the inner layer and one with layer and one with lower thermal conductivity for the outer 
  B. Material with lower thermal conductivity should be used for the inner layer and one with higher thermal conductivity for the outer 
  C. It is immaterial in which sequence the insulating materials are used 
  D. None of these
• Answer
• Ans. B
• Explanation

• [accordion]
• 8. Critical thickness of insulation for spheres is given by ______.  
• A. k/h 
  B. k/4h 
  C. h/2k 
  D. 2k/h
• Answer
• Ans. D
• Explanation

• [accordion]
• 9. Which surface will have the least emissivity?  
• A. Smooth glass 
  B. Plaster 
  C. Aluminum foil       
  D. Concrete
• Answer
• Ans. C
• Explanation

• [accordion]
• 10. The process of heat transfer from one particle of the body to another without the actual motion of the particle, is known as _________.  
• A. Conduction 
  B. Convection 
  C. Radiation 
  D. All options are correct
• Answer
• Ans. A Sol
• Explanation

• [accordion]
• 11. The process of heat transfer from a hot body to a cold body is straight line, without affecting the intervening medium, is known as ________.  
• A. Conduction 
  B. Convection 
  C. Radiation 
  D. All options are correct 
• Answer
• Ans. C
• Explanation

• [accordion]
• 12. Heat is transferred from an electric bulb by _____.  
• A. Conduction 
  B. Convection 
  C. Radiation 
  D. All options are correct 
• Answer
• Ans. C
• Explanation

• [accordion]
• 13. Assumption made in the Fourier’s law is that the heat flow  
• A. Is in steady state 
  B. Though a solid medium in one dimension 
  
  A. Only (A) 
  B. Only (B) 
  C. Both (A) and (B)
  D. None of these
• Answer
•  Ans. C 
• Explanation

• [accordion]
• 14. If thermal conductivity of a material of wall varies as K_0 (1 + 𝛼t), then the temperature at the centre of the wall as compared to that in case of constant thermal conductivity, will be __________.  
• A. More 
  B. Less 
  C. Same 
  D. Depend on other factors 
• Answer
• Ans. A 
• Explanation

• [accordion]
• 15. With increase in temperature, thermal conductivity of air _________.  
• A. Increases 
  B. Decreases 
  C. Remains the same 
  D. None of these
• Answer
•  Ans. A
• Explanation

• [accordion]
• 16. Liquid metal having highest thermal conductivity is of _________.  
• A. Sodium 
  B. Potassium 
  C. Lead 
  D. Mercury 
• Answer
• Ans. A
• Explanation

• [accordion]
• 17. Minimum thermal diffusivity is of ___________.  
• A. Aluminum 
  B. Rubber 
  C. Iron 
  D. Lead 
• Answer
• Ans. B 
• Explanation

• [accordion]
• 18. Critical radius of a hollow cylinder is defined as ________.  
• A. Outer radius which gives maximum heat flow 
  B. Outer radius which gives minimum heat flow 
  C. Inner radius which gives minimum heat flow 
  D. Inner radius which gives maximum heat flow
• Answer
• Ans. A 
• Explanation

• [accordion]
• 19. Heat exchangers are used in  
• A. Condensers and boilers in steam plants 
  B. Radiators 
  C. Intercoolers and preheaters 
  D. Condensers and evaporators in refrigerators and air conditioners 
  
  A. Only A 
  B. Only B 
  C. Only C 
  D. A, B, C and D 
• Answer
• Ans. D
• Explanation

• [accordion]
• 20. Automobile radiator is a heat exchanger of ________ type.  
• A. Counter flow 
  B. Parallel flow 
  C. Cross flow 
  D. Regenerator 
• Answer
• Ans. C
• Explanation

• [accordion]
• 21. For a closed system, difference between the heat added to the system and work done by the gas, is equal to the change in ___________.  
• A. Enthalpy 
  B. Entropy 
  C. Internal energy
  D. Temperature 
• Answer
• Ans. C 
• Explanation

• [accordion]
• 22. The sequence of process that eventually returns the working substance to its original state, is known as __________.  
• A. Event   
  B. Thermodynamic cycle 
  C. Thermodynamic property 
  D. None of these 
• Answer
• Ans. B
• Explanation

• [accordion]
• 23. According to Kelvin-Plank’s statement, a perpetual motion machine of ______.  
• A. First kind is possible 
  B. First kind is impossible 
  C. Second kind is impossible 
  D. Second kind is possible 
• Answer
• Ans. C
• Explanation

• [accordion]
• 24. According to kinetic theory of gases, at absolute zero ___________.  
• A. Specific heat of molecules reduces to zero 
  B. Kinetic energy of molecules reduces to zero 
  C. Volume of gas reduce to zero 
  D. Pressure of gas reduce to zero 
• Answer
• Ans. B
• Explanation

• [accordion]
• 25. According to Gay-Lussac’s law for perfect gases, the absolute pressure of given mass varies directly as ___________.  
• A. Temperature 
  B. Absolute temperature 
  C. Absolute temperature, if volume remains  constant 
  D. Product of absolute temperature and volume 
• Answer
• Ans. C
• Explanation

• [accordion]
• 26. Three states of matter are distinguished with respect to molecules by the _________. 
•  A. Atoms in molecules 
  B. Number 
  C. Orientation 
  D. Character of motion 
• Answer
• Ans. D
• Explanation

• [accordion]
• 27. Equal volume of all gases, at the same temperature and pressure, contain equal number of molecules. This is according to ___________.  
• A. Charle’s law 
  B. Avagardo’s law 
  C. Joule’s law 
  D. Gay Lussac law 
• Answer
• Ans. B
• Explanation

• [accordion]
• 28. Specific heat of a gas, Cp = Cv, at  
• A. Absolute zero 
  B. Critical temperature 
  C. Triple point 
  D. All temperature 
• Answer
• Ans. A
• Explanation

• [accordion]
• 29. The specific heat at constant volume of solids obeys Debye’s T3 law at _________.  
• A. High temperatures 
  B. Low temperatures 
  C. High pressures 
  D. All temperatures 
• Answer
• Ans. D 
• Explanation

• [accordion]
• 30. A reversible process _________.  
• A. Must pass through a continuous series of  equilibrium states 
  B. Leaves no history of the events in surroundings 
  C. Must pass through the same states on the  reversed path as on the forward path
  D. All options are correct 
• Answer
• Ans. D
• Explanation

To be continued