Quiz: Mechanical Engineering 14 April 2020

Quiz: Mechanical Engineering
Exam: ISRO
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes
Q1. Which one of the following gear tooth failures is induced when maximum Hertz contact stress on gear tooth surface exceeds surface endurance strength of tooth?
(a) Abrasive strength
(b) Corrosive wear
(c) Galling
(d) Destructive pitting
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10
Q2. V-belts follows
(a) Have low reduction ratio
(b) Due to wedging action slip is negligible
(c) Transmits power over long center distances
(d) All of the above
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10

Q3. A Quasi-static process
(a) is infinitely slow process
(b) experiences thermodynamic equilibrium at every small point on its path
(c) is reversible process
(d) all of the above
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10
Q4. The irreversibility in the system caused by friction is an example of
(a) frictional irreversibility
(b) external irreversibility
(c) internal irreversibility
(d) chemical irreversibility
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10
Q5. The ideal gas-refrigeration cycle is work on
(a) Brayton cycle
(b) Reversed Rankine cycle
(c) Rankine cycle
(d) Reversed Brayton cycle
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10
Q6. The product of force (F) and time-period (∆t) is called as________.
(a) momentum
(b) work done
(c) impulse
(d) pressure
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10

Q7. Which of the following is an example of impulse turbine?
(a) Propeller turbine
(b) Pelton wheel
(c) Kaplan turbine
(d) Francis turbine
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10
Q8. Copper when alloyed with zinc is known as
(a) Babbit
(b) Bronze
(c) Brass
(d) All of the above
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10

Q9. The grinding process is known for good surface finishing because
(a) the chip removed during the process is small
(b) the process is carried out at high cutting speed
(c) both a. and b
(d) none of the above
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10

Q10. Which of the following factors affecting selection of casting process?
(a) Tolerances
(b) Surface finish
(c) Both a. and b.
(d) None of the above
L1Difficulty 3
QTags Mechanical
QCereator Paper Maker 10

SOLUTIONS:-
S1. Ans(d)
Sol. Destructive pitting generally results from surface overload conditions which cannot be alleviated by initial pitting. destructive pitting can be avoided by keeping the load on the surface below the endurance limit for the material.
S2. Ans(b)
Sol.
S3. Ans(d)
Sol.
S4. Ans(c)
Sol. All the spontaneous processes are irreversible in nature. The irreversibility is caused by finite potential gradient like temperature gradient etc. or by any dissipative effect like friction. Types of irreversibility
1. Internal irreversibility
2. External irreversibility
1. Internal irreversibility:- Internal irreversibility is caused by internal dissipative effects in the system like friction, turbulence, electric resistance etc. Thus, the irreversibility in the system caused by friction is an example of internal irreversibility.
S5. Ans(d)
Sol. Ideal gas-refrigeration cycle work on the principle of Bell-coleman or reversed Brayton cycle. Air is used as a refrigerant.
S6. Ans(c)
Sol. Impulse is defined as the average impact force applied for a fraction of time.
i.e. I=F.∆t
S7. Ans(b)
Sol. Force of water acts tangentially to the Pelton wheel.
S8. Ans(c)
Sol. Brass has copper 70% and zinc 30%.
S9. Ans(c)
Sol. Low depth of cut and high cutting speed causes good surface finish in grinding process.
S10. Ans(c)
Sol.

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