UPSC Recruitment Paper 2017 : Posts of Additional Assistant Director (Safety) (Mechanical)

1. A fan consumes 20 W of electric power and discharges air from a ventilated room at 0.25 kg/s. The maximum air outlet velocity is nearly
(a) 4.7 m/s
(b) 8.7 m/s
(c) 10.2 m/s
(d) 12.7 m/s

2. Which one of the following statements is correct? 
(a) A machine which violates Clausius statement will violate the first law of thermodynamics
(b) A machine which violates Kelvin-Plank statement will violate the first law of thermodynamics
(c) A machine which violates the second law of thermodynamics will violate the first law of thermodynamics
(d) A machine which violates Kelvin-Plank statement will violate the Clausius statement

3. 150 Kj of heat is transferred from a heat source of 527°C to a heat sink at 127°C . If the ambient temperature is 47°C , the loss of available energy during the process will be
(a) 40 Kj
(b) 50 Kj
(c) 60 Kj
(d) 70 Kj

4. Which one of the following is correct in the context of change of entropy of a system undergoing a reversible adiabatic process?
(a) Positive for expansion process and negative for compression process
(b) Positive for compression process and negative for expansion process
(c) Negative for both the processes
(d) Positive for both the processes

5. Consider the following devices:
1. Internal combustion engine working on Otto cycle
2. Internal combustion engine working on Diesel cycle
3. Gas turbines
4. Steam turbines
In which of the above devices, the equation dQ=dU+Pdv  is not applicable?
(a) 2 and 3
(b) 1 and 4
(c) 3 and 4
(d) 1 and 2
 
6. Consider the following statements with reference to gas turbine cycle:
1. Regeneration increases thermal efficiency
2. Reheating decreases thermal efficiency
3. Cycle efficiency increases when the maximum temperature of the cycle is increased
Which of the above statements are correct?
(a) 1, 2 and 3
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1 and 3 only

7. For the same pressure ratio during compression, compressing in two-stage compressor with perfect inter-cooling instead of a single-stage compressor is characterized by:
1. Increase in volumetric efficiency
2. Decrease in work input
3. Decrease in discharge temperature
Which of the above statements are correct?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

8. What is the compression ratio of a 4-stroke engine whose capacity is 245 cc,clearance volume is 27.2 cc and diameter of bore is 10 % higher than stroke?
(a) 9
(b) 10
(c) 11
(d) 12

9. Thorium breeder reactors are more promising for India essentially because
(a) They develop more power
(b) The technology thereof is simple
(c) Thorium deposits are abundantly available in the country
(d) These can be easily designed

10. If Nusselt number is 4000 with corresponding Reynolds and Prandtl numbers as 40 and 20 respectively, the relevant Stanton number will be
(a) 40
(b) 20
(c) 10
(d) 5

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Courtesy:UPSC