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NHPC JE’21 ME: Daily Practices Quiz. 30-Sep-2021

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NHPC-JE’21 ME: Daily Practices Quiz

NHPC-JE’21 ME: Daily Practices Quiz 30-Sep-2021

Quiz: Mechanical Engineering
Exam: NHPC JE
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes

Q1. An oil of specific gravity 0.9 has viscosity of 0.28 stokes at 38°C. What will be its viscosity in Ns/m²?
(a) 0.2520
(b) 0.0311
(c) 0.0252
(d) 0.0206

Q2. What is the pressure difference between inside and outside of a droplet of water?
(a) 2σ/d
(b) 4σ/d
(c) 8σ/d
(d) 12σ/d
Where σ is surface tension and d is the diameter of the droplet.

Q3. Strain rosettes are generally used for
(a) measurement of load
(b) measurement of shear strain
(c) measurement of longitudinal strain
(d) measurement of resilience

Q4. Stress-strain analysis is conducted to know which of the following properties of material?
(a) Physical properties
(b) Optical properties
(c) Mechanical properties
(d) Magnetic properties

Q5. Weber number is defined as the ratio of inertia force to
(a) Viscous force
(b) Elastic force
(c) Surface tension force
(d) Gravity force

Q6. What is an azeotrope?
(a) A halogenic refrigerant
(b) A refrigerant dissolved in alcohol
(c) A mixture of refrigerants without phase separation
(d) Mixture of two crystal structure

Solutions

 

S1. Ans (c)
Sol. Dynamic viscosity,
μ=ρυ=(0.9×1000)×(0.28×10^(-4) )
=0.0252 Ns/m²

S2. Ans (b)
Sol. Pressure difference between inside and outside of a droplet of water = 4σ/d
∵ Bursting force = p×πd²/4
Resisting force = σ ×π d
Bursting force= Resisting force
p×πd²/4=σ×πd
or p=4σ/d

S3. Ans. (c)
Sol. strain rosettes are generally used for measurement of longitudinal strain.
A strain gauge rosette is a term for an arrangement of two or more strain gauges that are positioned closely to measure strains along different directions of the component under evaluation. Single strain gauges can only measure strain effectively in one direction, so the use of multiple strain gauges enables more measurements to be taken, providing a more precise evaluation of strain on the surface being measured.

S4. Ans. (c)
Sol. stress- strain analysis is conducted to know the Mechanical properties of materials.

S5. Ans.(c)
Sol.
Weber number:
W=((Inertia force)/(Surface tension))^(1/2)=V/√(σ/ρL)
Mach number:
M=((Inertia force)/(Elastic force))=V/√(K/ρ)
Euler number:
E=((Inertia force)/(Pressure force))^(1/2)=V/√(p/ρ)

S6. Ans.(c)
Sol. Azeotrope is a mixture of refrigerants without phase separation.

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Published by VINAYAK KUMAR

Graduated from BIT Sindri, Postgraduated from IIT BHU Varanasi

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