Quiz:Mechanical Engineering 8 April 2020

Quiz: Mechanical Engineering
Exam: ISRO (TECHNICAL ASST.)
Topic: Miscellaneous

Each question carries 4 mark.
Negative marking: 1 mark
Time: 15 Minute

Q1. Fraction of radiative energy leaving one surface that strikes the other surface is called
(a) Radiative flux
(b) Emissive power of the first surface
(c) View factor
(d) Re-radiation flux

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q2. In a boiler, the air preheater is invariably located between:
(a) Forced draft fan and chimney
(b) Forced draft fan and furnace
(c) Economizer and feed pump
(d) Condenser and feed pump

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q3. Consider the following processes:
1. Constant pressure heat addition
2. Adiabatic compression
3. Adiabatic expansion
4. Constant pressure heat rejection
The correct sequence of these process in Rankine cycle is:
(a) 1, 2, 3, 4
(b) 2, 1, 4, 3
(c) 2, 1, 3, 4
(d) 1, 2, 4, 3

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q4. The pressure center is
(a) the centroid of the pressure prism
(b) a point on the line of action of the resultant force
(c) at the centroid of the submerged area
(d) always above the centroid of the area

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q5. In milk chilling plants, the usual secondary refrigerant is
(a) Ammonia solution
(b) Sodium Silicate
(c) Glycol
(d) Brine

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q6. If the time taken by a system to execute a process through a finite gradient is infinitely large, the process
(a) becomes reversible
(b) is irreversible
(c) becomes isothermal
(d) is adiabatic

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q7. Which one of the following relationships defines the Helmholtz function F?
(a) F=H+ TS
(b) F=H– TS
(c) F=U – TS
(d) F= U+ TV

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q8. The problem of interference in involute profile gears can be overcome by which one of the following means?
(a) Decreasing the center distance
(b) Using composite profile with cycloidal curve at the root of the tooth
(c) Using stub teeth of height more than the full depth teeth
(d) Proper lubrication

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q9. A constitutional diagram shows relationship among which of the following combinations in a particular alloy system?
(a) temperature and composition
(b) temperature and phases present
(c) temperature, composition and phases present
(d) temperature and pressure

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Q10. Which of the following statements are correct for temperature rise in metal cutting operation?
1. it adversely affects the properties of tool material.
2. It provides better accuracy during machining.
3. It causes dimensional changes in workpiece and affects accuracy of machining.
4. It can distort the accuracy of machine tool itself.
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4 only
(d) 1, 3 and 4

L1Difficulty 3
QTags Mechanical
QCreator Paper Maker 10

Solutions

S1. Ans (c)
Sol.The view factor is the fraction of radiative energy that diffused from one surface element and strikes the other surface directly.

S2. Ans (b)
Sol.Air preheater is invariably located between forced draft fan and furnace to preheat the combustion air.

S3. Ans (c)
Sol.

S4. Ans (b)
Sol.The canter of pressure is the point on a body where the total sum of a pressure field acts, causing a force and no moment about that point.

S5. Ans (d)
Sol.Brine is used as secondary refrigerant in milk chilling plant.

S6. Ans (c)
Sol.Process execution through a finite gradient of time is irreversible.
Here, time gradient is so large that temperature remains constant and hence the process becomes isothermal.

S7. Ans (c)
Sol.

S8. Ans.(b)
Sol.
Techniques to avoid interference –
(1) Stubbing of teeth i.e. height of teeth is reduced.
(2) Undercutting of teeth at base
(3) Increasing the center distance of gears or using large pressure angle
(4) Increasing the no. of teeth on gear can avoid interference.

S9. Ans.(c)
Sol.

S10. Ans.(d)
Sol. The rise of temperature of work piece and tool give rise to
(i) Early wear of tool
(ii) Dimensional in-accuracy of machined surface
(iii) Damage of surface properties of machined component.
So, statement 2 is wrong

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