Quiz: Mechanical Engineering 15 May 2020

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

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

Q1. A box that can represent two different condition in a flow chart is
(a) Circle
(b) Square
(c) Diamond
(d) Parallelogram

Q2. For an irreversible adiabatic process
(a) dS=dQ/T
(b) dS>dQ/T
(c) dS<dQ/T
(d) dS>0

Q3. Flow work is valid for
(a) Closed system
(b) Reversible process
(c) Open system
(d) Isolated system

Q4. In what form solar energy is radiated from the sun?
(a) Ultraviolet radiation
(b) Infrared radiation
(c) Electromagnetic radiation
(d) Transverse waves

Q5. Two infinite parallel plates are kept at a distance x. The value of shape factor is
(a) Two
(b) Zero
(c) One
(d) Infinite

Q6. Which one of the following turbines needs maximum head?
(a) Kaplan turbine
(b) Pelton turbine
(c) Francis turbine
(d) Reaction turbine

Q7. What should be the pH value of feed water used in the boilers?
(a) 0
(b) 7
(c) >7
(d) <7

Q8. For products subjected to large vibrations, which of the joint is better?
(a) Threaded
(b) Hinged
(c) Welded
(d) Ball and socket

Q9. The Coriollis acceleration leads the sliding velocity by
(a) 45°
(b) 90°
(c) 180°
(d) 135°

Q10. Set screws can be subjected to
(a) Tensile load only
(b) Compressive load only
(c) Both tensile and compressive load only
(d) Neither tensile nor compressive load

Solutions

S1. Ans (c)
Sol. Diamond box is used to give a condition for decision making in a flow chart.

S2. Ans (d)
Sol. We know that
dS=δQ/T+δS(entropy-generation)
For adiabatic process,
δQ=0
Hence, for irreversible adiabatic process,
dS= δS(entropy-generation)
dS>0

S3. Ans (c)
Sol. Flow work is analogous to displacement work and is defined as the work needed to displace a fluid element from one point to another. It is valid for open system. E.g. Turbine, compressor etc.

S4. Ans (c)
Sol. Most of the radiation emitted from the sun in form of solar radiation are electromagnetic waves. 99% of the solar radiation are visible and infrared radiation and rest is ultraviolet radiation.

S5. Ans (c)
Sol. Shape factor or view factor of a body with respect to another body is defined as the part of radiation emitted from one body to another body.
If two infinite parallel plates are kept at a distance x then whole of the radiation emitted from one plate will project on another body. Hence, view factor is 1.

S6. Ans (b)
Sol. Pelton turbine is a high head turbine and head needed for this turbine ranges from 50 meter to 1500 m.

S7. Ans (c)
Sol. pH of boiler feed water should be greater than 7 because water needed for the boiler should not be acidic otherwise it will corrode boiler tubes and other parts. Normal range of pH should be 7.8 to 8.9.

S8. Ans (c)
Sol. When the joint is subjected to large vibration then it should be welded, so that it will not be loosen.

S9. Ans (b)
Sol. Coriollis acceleration acts on a sliding body which is sliding on a rotating body, such as slotted-lever quick return motion mechanism. Coriollis acceleration leads the sliding velocity of slider by 90°.

S10. Ans (b)
Sol. Set screws exerts compressional or clamping force through the bottom tip that projects through the hole.

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