Legal Metrology • Mechanical Engineering Paper-I
What are the dimensions of kinematic viscosity of a fluid?
A)
LT
B)
LT-1
C)
ML-1T-1
D)
ML2T-2
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is 'ML-1T-1' (Option C).
Legal Metrology • Mechanical Engineering Paper-I
The chemical formula of Freon-12 is
A)
CCl₂F₂
B)
CCl₃F
C)
CClF₃
D)
CCl₄F
Freon-12 (R-12) is dichlorodifluoromethane, CCl₂F₂.
Legal Metrology • Mechanical Engineering Paper-I
To avoid a correction for the effect of capillary in manometers, the minimum diameter of tube (in mm) should be
A)
2.5
B)
6
C)
10
D)
15
A manometer tube of about 6 mm or more minimizes capillary correction.
Legal Metrology • Mechanical Engineering Paper-I
Which of the following parameters remain constant during a sensible cooling or heating process?
A)
humidity ratio
B)
relative humidity
C)
enthalpy
D)
wet bulb temperature
Sensible cooling/heating changes temperature without adding/removing moisture, so humidity ratio remains constant.
Legal Metrology • Mechanical Engineering Paper-I
Choose the open thermodynamic system
A)
manual ice cream freezer
B)
centrifugal pump
C)
pressure cooker
D)
battery
A centrifugal pump involves mass flow in and out, categorizing it as an open thermodynamic system.
Legal Metrology • Mechanical Engineering Paper-I
Which of the following forces act on a fluid at rest?
(i) gravity force (ii) hydrostatic force
(iii) surface tension (iv) viscous force
A)
i, ii, iii and iv
B)
i, ii and iii
C)
ii and iv
D)
i, iii, iv
In a fluid at rest, shear stresses are zero. Only gravity and hydrostatic forces act on it.
Legal Metrology • Mechanical Engineering Paper-I
When is a pressure reducing valve used?
A)
it is used when higher pressure than system pressure is required
B)
it is used when lower pressure than system pressure is required
C)
when absolutely zero pressure is required
D)
all of the above
A pressure-reducing valve is used when the downstream/system pressure must be lower than the upstream pressure.
Legal Metrology • Mechanical Engineering Paper-I
A unit cubic metre of water is subjected to a pressure of 10 bar. Then a change in the volume of water amounts to m³ when bulk modulus K = 2 x 10⁹ Pa.
A)
1/20
B)
1/200
C)
1/2000
D)
1/3000
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is '1/2000' (Option C).
Legal Metrology • Mechanical Engineering Paper-I
Which dimensionless number has significant role in forced convection?
A)
Prandtl number
B)
Reynolds number
C)
Mach number
D)
Peclet number
Reynolds number is the principal dimensionless group for forced convection and characterizes inertial/viscous effects.
Legal Metrology • Mechanical Engineering Paper-I
Molecular transmission of heat is smallest in case of
A)
gases
B)
liquids
C)
solids
D)
alloys
Gas has the lowest thermal conductivity of the three common states, so molecular transfer of heat is least effective there.
Legal Metrology • Mechanical Engineering Paper-I
An increase in convective coefficient over a fin
A)
increases effectiveness
B)
decreases effectiveness
C)
does not influence effectiveness
D)
influences only the fin efficiency
Increasing h raises heat transfer from a fin, generally improving fin effectiveness.
Legal Metrology • Mechanical Engineering Paper-I
Which factor is considered while selecting the diameter of piston rod in hydraulic cylinder?
A)
bore diameter
B)
length of stroke
C)
load
D)
all of the above
Piston-rod sizing depends on load, stroke/buckling length, and cylinder geometry/bore; hence all listed factors matter.
Legal Metrology • Mechanical Engineering Paper-I
The pressure inside a soap bubble of 50 mm diameter is 25 N/m² above the outside atmospheric pressure. The surface tension in soap film would be N/m.
A)
0.156
B)
0.312
C)
0.624
D)
0.078
For a soap bubble, Δp=4σ/r? equivalently Δp=8σ/d. With d=0.05 m, σ=25×0.05/8=0.156 N/m, so A is the standard bubble formula answer.
Legal Metrology • Mechanical Engineering Paper-I
Which one of the following quantities presents the property of a system?
A)
∫p dv
B)
∫v dp
C)
∫(dv + v dp)
D)
none of these
∫(dv + v dp) simplifies to the exact differential d(pv), making it a point function or property.
Legal Metrology • Mechanical Engineering Paper-I
A balloon lifting in air follows the following principle
A)
Law of gravitation
B)
Archimedes Principle
C)
Principle of buoyancy
D)
All of the above
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is 'All of the above' (Option D).
Legal Metrology • Mechanical Engineering Paper-I
Free convection heat flows depends on all of the followings, except
A)
density
B)
coefficient of viscosity
C)
gravitational force
D)
velocity
Free convection depends on buoyancy, density, viscosity, temperature difference, etc., not an imposed velocity.
Legal Metrology • Mechanical Engineering Paper-I
Which of the following is the lightest and most volatile liquid fuel?
A)
Diesel
B)
Kerosene
C)
Fuel oil
D)
Gasoline
Gasoline is lighter and more volatile than diesel, kerosene, and fuel oil.
Legal Metrology • Mechanical Engineering Paper-I
Clausius inequality is applied at
A)
reversible isothermal heat addition
B)
reversible adiabatic expansion
C)
reversible isothermal compression
D)
reversible isothermal heat rejection
Clausius inequality is based on reversible isothermal heat transfer logic in cycles.
Legal Metrology • Mechanical Engineering Paper-I
Which of the following statements are true?
i) piston pumps are self-priming
ii) piston pumps require high maintenance
iii) piston pumps have low cost of production
iv) piston pumps have low volumetric efficiency
A)
i and ii
B)
iii and iv
C)
i and iii
D)
all of the above
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is 'all of the above' (Option D).
Legal Metrology • Mechanical Engineering Paper-I
The vapour compression refrigeration employs the following cycle
A)
Reverse carnot
B)
Carnot
C)
Rankine
D)
Brayton
The vapor-compression refrigerator approximates a reversed Rankine cycle.
Legal Metrology • Mechanical Engineering Paper-I
Increasing the number of reheating stages in a gas turbine to infinity makes the expansion tending
A)
reversible adiabatic
B)
isothermal
C)
isobaric
D)
adiabatic
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is 'isobaric' (Option C).
Legal Metrology • Mechanical Engineering Paper-I
All liquid surfaces tend to stretch. This phenomenon is called
A)
Cohesion
B)
adhesion
C)
surface tension
D)
cavitation
Surface tension causes a liquid surface to behave like a stretched elastic membrane.
Legal Metrology • Mechanical Engineering Paper-I
A quasi static process is one in which all the states through which a system passes are very close to
A)
equilibrium state
B)
original state
C)
same temperature
D)
each other
A quasi-static process occurs infinitely slowly so that the system is always in a state of thermodynamic equilibrium.
Legal Metrology • Mechanical Engineering Paper-I
Heat is conducted through a 10 cm thick wall at the rate of 30 W/m² when the temperature difference across the wall is 10 °C. What is the thermal conductivity (Wm/K) of the wall material?
A)
0.03
B)
0.3
C)
3.0
D)
30
k=qL/ΔT=(30)(0.10)/10=0.30 W/(m·K).
Legal Metrology • Mechanical Engineering Paper-I
Standard air is air at
A)
1 bar pressure and 0°C temperature
B)
1 bar pressure and 15°C temperature
C)
1 bar pressure, 20°C temperature and 36% relative humidity
D)
atmospheric conditions of pressure and temperature at any specific location
In the context of Mechanical Engineering, the most appropriate and technically accurate answer is '1 bar pressure, 20°C temperature and 36% relative humidity' (Option C).
