Job Questions (Part 1)

Mechanical Engineering Jobs Questions with answers:-
01. Write down about Jigs. Bangladesh Bank -12
Answer: Jigs are used for holding and guiding the tool in drilling, reaming or tapping operations.
02. Write down about fixtures. Bangladesh Bank-12
Answer: Fixtures are used for holding the work in milling, grinding, planning or turning operations.
03. What is Newtonian Fluid? RPCL-13
Answer: A fluid whose viscosity does not change with the rate of deformation or shear strain is known as Newtonian fluid.
04. Write down the lathe operation. Bangladesh Bank -12
Answer: Operations which can be carried out on a lathe are as follows-
            Knurling, Threading, Boring, Chamfering, Taper turning, Plain turning, Step turning
05. What is the composition of Babbit metal? Asuganj Power Station
Answer: A tin base alloy containing 88% tin, 8% antimony and 4% copper is called Babbit metal.
06. Define Co-efficient of contraction. Bangladesh Bank -12
Answer: It is defined as the ratio of area of jet at Vena Contracta (ac) to the area of orifice (a).
07. Define of Co-efficient of velocity.
Answer: It is defined as the ratio of the actual velocity of the jet at vena contracta.
08. What is cavitation? Bangladesh Bank -12
Answer: The formation, growth and collapse of vapor filled cavities or bubbles in a flowing liquid due to local fall in fluid pressure are called cavitation.
09. Write down some refrigerants.
Answer: List of refrigerants are mostly used-
a) R-11 (CCl3F) : Boiling Point 23.770C
b) R-12  (CCl2F2): Boiling Pint -290C
c) R-22 (CHClF2): Boiling Point -410C
d) Ammonia (NH3): Boiling Point -33.330C
10. What is system? Bangladesh Bank -13
Answer: The thermodynamic system may be defined as a definite area or space where some thermodynamic process takes place. The thermodynamic system may be classified into the following three groups.
Closed System
Open System
Isolated System
 11. What is cetane Number?
Answer: The percentage by volume of cetane in a mixture of cetance & α-methyl naphthalene which has the same ignition delay as the given fuel when tested in a specified test engine under specified condition is as cetane number. e.g. If a fuel has cetane number 45, it means that the fuel is having the same ignition delay as a mixture of 45% cetane and 55% α-methyl naphthalene by volume.
 12. Comparison between petrol Engine and Diesel Engine. BRTA-12
Petrol Engine
Diesel Engine
A Petrol Engine draws a mixture of petrol and air during suction stroke.
A Diesel Engine only draws air during suction stroke.
The pressure at the end of compression is 10 bar.
The pressure at the end of compression is 35 bar.
The combustion of fuel takes place approximately at constant volume.
The combustion of fuel takes place approximately at constant pressure.
A Petrol Engine compression ratio approximately.
A diesel Engine compression ratio approximately from 15 to 25.
The thermal efficiency is upto about 26%.
The thermal efficiency is upto about 40%.
 13. For a small scale industry, the fixed cost per month is Tk. 500 The variable cost per product is Tk. 20 and sell price is Tk. 30 per price. The Break even production per month? BOF
X= Break even Production per month
5000 + 20X = 30 X
X= 500
 14.  What are Boiler mountings? Write down their name. Bangladesh Bank-13
Answer: These are the fittings, which are mounted on the boiler for its proper and safe functioning.
Water level Indicator, Pressure Gauge, Safety valves, Steam stop valve, Blow-off-Cock, Fusible plug.
 15. What is stiffness of a spring? PDB-12, Asuganj -13
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