Quiz: Mechanical Engineering 27 July 2020

Quiz: Mechanical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes

Q1. Which of the following is another name of reversible adiabatic process?
(a) Isothermal process
(b) Isochoric process
(c) Isentropic process
(d) none of these

Q2. Which of the following is correct for Hart mechanism?
(a) It consists of eight links
(b) It consists of six links
(c) It consists of four links
(d) It consists of twelve links

Q3. Which of the following type of loads acts on a rotating shaft carrying a unidirectional
transverse load?
(a) Variable bending stress
(b) Variable shear stress
(c) Constant bending stress
(d) Constant shear stress

Q4. Which of the following represents the compositions of photo-chemical smog?
(a) NOX and HC
(b) CO and CO2
(c) Excess O2
(d) Soot and PM

Q5. When a ship enters the Ganga river from Bay of Bengal, Which of the following things
will occur?
(a) Ship will rise a little
(b) Ship will fall a little
(c) It remains at same level
(d) It depends upon boat density

Q6. To accomplish which of the following needs, surge tank is used?
(a) To reduce frictional loss in pipe
(b) To ensure uniform flow in pipe
(c) To relieve the pressure due to water hammer
(d) To reduce cavitation

Q7. For what type of columns Euler’s formula is valid?
(a) Short column
(b) Both short and long column
(c) Weak column
(d) Long column

Q8. What type of gears we use, if the velocity reduction ratio is above 100?
(a) Spur gear
(b) Worm and worm gear
(c) Helical gear
(d) Bevel gear

Q9. The effects of work transfer from a high-pressure body to a low-pressure body are:
1. The energy is conserved
2. The entropy is not conserved
3. The availability is not conserved
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

Q10. Which of the following devices is used to heat feed-water by utilizing the heat of the exhaust flue gases before leaving through the chimney?
(a) Superheater
(b) Economizer
(c) Air preheater
(d) ID fan

Solutions

S1. Ans (c)
Sol. A Reversible Adiabatic Process is also known as Isentropic Process. It is an idealized thermodynamic process which is adiabatic and in which the work transfers of the system are frictionless; there is no transfer of heat or of matter and the process is reversible.

S2. Ans.(b)
Sol. Hart mechanism consists of six links.

S3. Ans.(a)
Sol. Some fibre is subjected to tensile and compressive bending tress.

S4. Ans (a)
Sol. Photo-chemical smog is produced when pollutants from the combustion of fossil fuels react with sunlight. The energy in the sunlight converts the pollutants into other toxic chemicals. In order for photo-chemical smog to form, there must be other pollutants in the air, specifically nitrous oxides and other volatile organic compounds (VOCs).

S5. Ans (b)
Sol. Due to density of sea water is more than that of river water, hence more volume of boat has to be sunk in the river water than that in sea water.so floor level will fall of boat in river water.

S6. Ans.(c)
Sol. Surge tank is an open reservoir provided in between penstock to
(i) absorb the pressure wave due to sudden blockage of flow in the turbine which will reduce water pressured hammer problem
(ii) to serve for emergency supply and to maintain constant head at inlet of turbine

S7. Ans.(d)
Sol. As long column fails in buckling only, Euler formula also derived at the same assumption.

S8. (b)
Sol. For high velocity reduction ratio (more than 50), we use worm and worm wheel gear drive.

S9. Ans.(d)
Sol. When there is a decrease in pressure (High to low), then there is always an entropy
generation and loss of availability according to second law of thermodynamics. But energy
is always conserved according to first law of thermodynamics

S10. Ans.(b)
Sol. Economizer is situated before air pre-heater in the flue gas path.

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