Title: Mechanical Engineering 7 April 2020

Quiz: Mechanical Engineering
Exam: UPSSSC JE
Topic: Miscellaneous

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

Q1. Reversible adiabatic process is also called
(a) Isothermal process
(b) Isochoric process
(c) Isentropic process
(d) none of these

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q2. Hart mechanism has
(a) eight links
(b) six links
(c) four links
(d) twelve links

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q3. A rotating shaft carrying a unidirectional transverse load is subjected to:
(a) Variable bending stress
(b) Variable shear stress
(c) Constant bending stress
(d) Constant shear stress

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q4. Photo-chemical smog is mainly due to
(a) Nitrogen oxides and HC
(b) CO and carbon di-oxide
(c) Excess oxygen
(d) Soot and PM

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q5. When a boat enters river from a sea, one can expect
(a) to rise a little
(b) to fall a little
(c) to remain at same level
(d) depends upon boat density

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q6. Why are surge tanks used in pipe line?
(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

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q7. Euler’s formula holds good only for
(a) Short column
(b) Both short and long column
(c) Weak column
(d) Long column

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q8. If velocity reduction ratio is above 100 then we use
(a) Spur gear
(b) Worm and worm gear
(c) Helical gear
(d) Bevel gear

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q9. The effects of heat transfer from a high temperature body to a low temperature 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

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q10. The device used to heat feed-water by utilizing the heat of the exhaust flue gases before leaving through the chimney, is called
(a) Super heater
(b) Economizer
(c) Air preheater
(d) ID fan

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Solutions

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

S2. Ans.(b)
Sol.

S3. Ans.(a)
Sol. Some fiber 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 pen-stock 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.

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

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