Explore topic-wise MCQs in Mechanical Engineering Questions.

This section includes 585 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

1.

Which among the following methods for estimation of convective heat transfer coefficient are having some limitations? (1) Analogy between heat, mass and momentum transfer (2) Dimensional analysis coupled with experimental data (3) Approximate analysis of the boundary layer equation (4) Exact mathematical analysis of the boundary layer equation
A. (1), (2) and (3)
B. (2), (3) and (4)
C. (1), (2) and (4)
D. all of the given (1), (2), (3) and (4)
Answer» E.
Discussion
2.

At the critical radius of insulation of a hollow sphere, the heat transfer will be
A. minimum
B. maximum
C. does not change
D. unpredictable
Answer» C. does not change
Discussion
3.

The scales form in heat exchangers after a period of operation and provide additional resistance to heat transfer with some heat transfer coefficient. The reciprocal of this scale heat transfer coefficient is called as
A. scaling factor
B. fouling factor
C. forming factor
D. resisting factor
Answer» C. forming factor
Discussion
4.

Which of the following is the case of heat transfer by radiation ___________________?
A. blast furnace
B. heating of building
C. cooling of parts in furnace
D. heat received by a person from fireplace
E. all of the above
Answer» E. all of the above
Discussion
5.

A thorough knowledge of the mechanism is necessary for the estimate of convective heat transfer coefficient so that the process can be adequately represented by mathematical equation. This is a limitation of the method of
A. analogy between heat, mass and momentum transfer
B. approximate analysis of the boundary layer equation
C. dimensional analysis coupled with experimental data
D. exact mathematical analysis of the boundary layer equation
Answer» E.
Discussion
6.

Unit of thermal conductivity in M.K.S. units is ___________________?
A. kcal/kg m2 °C
B. kcal-m/hr m2 °C
C. kcal/hr m2 °C
D. kcal-m/hr °C
E. kcal-m/m2 °C
Answer» C. kcal/hr m2 °C
Discussion
7.

The term in the heat transfer system which is analogous to the electrical resistance is called as
A. thermal resistance
B. conductive resistance
C. potential resistance
D. none of the above
Answer» B. conductive resistance
Discussion
8.

A perfect black body is one which_______________?
A. is black in colour
B. reflects all heat
C. transmits all heat radiations
D. abslprbs heat radiations of all wave lengths falling on it
E. fully opaque
Answer» E. fully opaque
Discussion
9.

According to the Stefan-Boltzmann law of thermal radiation for a perfect radiator, the rate of radiant energy per unit area is proportional to
A. the temperature of that radiator
B. the square of the temperature of that radiator
C. the cube of the temperature of that radiator
D. the fourth power of the temperature of that radiator
Answer» E.
Discussion
10.

Mass transfer does not take place in
A. conduction heat transfer
B. convection heat transfer
C. radiation heat transfer
D. none of the above
Answer» D. none of the above
Discussion
11.

In which phase of a substance does conduction mode of heat transfer take place?
A. solid
B. liquid
C. gaseous
D. all of the above
Answer» E.
Discussion
12.

Heat transfer deals with the rate of
A. work transfer
B. temperature transfer
C. energy transfer
D. none of the above
Answer» D. none of the above
Discussion
13.

Which among the following has lowest thermal conductivity among the others?
A. silver
B. water
C. mercury
D. copper
Answer» C. mercury
Discussion
14.

In convection heat transfer energy transfer takes place between
A. two solid surfaces connected physically
B. solid surface and fluid system in motion
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
15.

In gases, the transfer of heat takes place by
A. volumetric density
B. transporting energy with free electrons
C. unstable elastic collision
D. random molecular collision
Answer» E.
Discussion
16.

How does the heat transfer take place in metals?
A. volumetric density
B. transporting energy with free electrons
C. unstable elastic collision d. random molecular collision
D. None of the above
Answer» C. unstable elastic collision d. random molecular collision
Discussion
17.

Which two processes are unitedly responsible in the transfer of heat between solid surface and surrounding fluid?
A. conduction and convection
B. conduction and mass transfer
C. convection and mass transfer
D. none of the above
Answer» C. convection and mass transfer
Discussion
18.

Internal energy of a substance is associated with
A. microscopic modes of energy
B. macroscopic modes of energy
C. both a. and b.
D. none of the above
Answer» B. macroscopic modes of energy
Discussion
19.

When the surface of a body is at higher temperature than the surrounding fluid, then the heat flows firstly from surface of the body to the adjacent layer of fluid by
A. convection
B. conduction
C. radiation
D. none of the above
Answer» C. radiation
Discussion
20.

The convection heat transfer coefficient depends upon
A. the thermal properties of fluid
B. geometry of the system
C. characteristics of the fluid flow
D. all of the above
Answer» E.
Discussion
21.

The fluid flow in which the fluid particles in one layer do not mix with the fluid particles in the other layer is called as
A. laminar flow
B. turbulent flow
C. layer flow
D. none of the above
Answer» B. turbulent flow
Discussion
22.

In a process of heat transfer by convection from a body to the surrounding fluid, the convection heat transfer coefficient
A. remains constant over the entire surface of the body
B. does not remain constant over the entire surface of the body
C. Both A & B
D. none of the above
Answer» C. Both A & B
Discussion
23.

Generally, all the fluid particles in flowing fluid
A. flow at a constant velocity
B. flow at various velocities
C. flow at a velocity as high as possible
D. none of the above
Answer» C. flow at a velocity as high as possible
Discussion
24.

Which surface does the drop-wise condensation occur on?
A. wettable surface
B. non-wettable surface
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
25.

The value of thermal conductivity k depends upon
A. the material through which the heat is transferred
B. the intensity of heat energy which is being transferred
C. the area which is parallel to the heat transfer
D. all of the above
Answer» B. the intensity of heat energy which is being transferred
Discussion
26.

How can the rates of heat transfer from drop-wise condensation and film condensation be compared?
A. the rate of heat transfer from drop-wise condensation is lower than that of film condensation
B. the rate of heat transfer from drop-wise condensation is higher than that of film condensation
C. the rate of heat transfer from drop-wise condensation is equal to that of film condensation
D. unpredictable
Answer» C. the rate of heat transfer from drop-wise condensation is equal to that of film condensation
Discussion
27.

The thermal resistance for heat transfer is low in
A. drop-wise condensation
B. film condensation
C. both drop-wise and film condensation
D. unpredictable
Answer» B. film condensation
Discussion
28.

Film condensation occurs on a surface when
A. condensate can wet all the surface
B. condensate cannot wet the surface
C. both a. and b.
D. none of the above
Answer» B. condensate cannot wet the surface
Discussion
29.

According to the Fourier's law of heat conduction, the rate of heat transfer by conduction depends upon
A. area of cross section normal to the heat flow
B. temperature gradient
C. both a. and b.
D. none of the above
Answer» D. none of the above
Discussion
30.

What is the relation between the rate of convection heat transfer and the rate of mixing in turbulent fluid flow?
A. the rate of convection heat transfer decreases with increase in the rate of mixing in turbulent fluid flow
B. the rate of convection heat transfer increases with increase in the rate of mixing in turbulent fluid flow
C. the rate of convection heat transfer does not affected by the change in the rate of mixing in turbulent fluid flow
D. none of the above
Answer» C. the rate of convection heat transfer does not affected by the change in the rate of mixing in turbulent fluid flow
Discussion
31.

The conduction heat transfer with combination of transfer of material also is called as
A. material conduction heat transfer
B. convection heat transfer
C. solid convection heat transfer
D. none of the above
Answer» C. solid convection heat transfer
Discussion
32.

Which phenomenon is related to the term radiation?
A. magnetic phenomenon
B. gravity
C. electromagnetic phenomenon
D. none of the above
Answer» D. none of the above
Discussion
33.

Why is the negative sign introduced in the equation of Fourier's law of heat conduction? q = – kA (dT / dx)
A. because heat transfer rate is inversely proportional to temperature gradient
B. because value of thermal conductivity k is negative
C. because heat is transferred from higher temperature to lower temperature
D. none of the above
Answer» D. none of the above
Discussion
34.

What is the temperature gradient in the conduction heat transfer?
A. change in temperature per unit change in time
B. change in temperature per unit change in distance in the direction of heat flow
C. change in temperature per unit change in cross-sectional area normal to the direction of heat flow
D. change in temperature per unit change in cross-sectional area parallel to the direction of heat flow
Answer» C. change in temperature per unit change in cross-sectional area normal to the direction of heat flow
Discussion
35.

The range of waves within which all possible frequencies of electromagnetic radiation are represented is called as
A. electromagnetic frequencies
B. electromagnetic spectrum
C. electromagnetic range
D. none of the above
Answer» C. electromagnetic range
Discussion
36.

The materials which have low thermal conductivity are called as ____________
A. thermal conductors
B. thermal resistors
C. thermal insulators
D. none of the above
Answer» D. none of the above
Discussion
37.

Thermal radiation takes place from a body by electromagnetic waves as a result of
A. the weight of the body
B. the magnetic power of the body
C. the temperature of the body
D. none of the above
Answer» D. none of the above
Discussion
38.

Which of the following is NOT a type of condensation heat transfer process?
A. drop-wise condensation
B. bulk-wise condensation
C. film-wise condensation
D. none of the above
Answer» C. film-wise condensation
Discussion
39.

The wavelength range of the visible light is about
A. 350 to 750 μm (micrometer)
B. 350 to 750 nm (nanometer)
C. 350 to 750 cm (centimeter)
D. none of the above
Answer» C. 350 to 750 cm (centimeter)
Discussion
40.

What is the approximate wavelength range of thermal radiation?
A. 0.1 to 100 μm (micrometer)
B. 0.1 to 100 nm (nanometer)
C. 0.1 to 100 cm (centimeter)
D. none of the above
Answer» B. 0.1 to 100 nm (nanometer)
Discussion
41.

What is the condition for conduction mode of heat transfer between two bodies?
A. the two bodies must be in physical contact
B. there must be temperature gradient between the bodies
C. both a. and b.
D. none of the above
Answer» D. none of the above
Discussion
42.

How is the wavelength of radiation (λ) calculated, when propagation velocity (C) and frequency (ν) of the radiation is given?
A. λ = C x ν
B. λ = C / ν
C. λ = ν / C
D. none of the above
Answer» C. λ = ν / C
Discussion
43.

Viscosity of a fluid can be defined as
A. change in density of the fluid per unit temperature
B. flow resistance offered by the fluid
C. flow velocity change
D. none of the above
Answer» C. flow velocity change
Discussion
44.

Which of the following bodies will not be able to emit radiation continuously?
A. a body with very high temperature placed in air medium
B. a body with temperature 0 °C placed in air medium
C. a body with temperature 0 °C placed in vacuum
D. none of the above
Answer» E.
Discussion
45.

What is emissive power of a body?
A. total radiation emitted by the body per unit volume and time
B. total radiation emitted by the body per unit temperature and time
C. total radiation emitted by the body per unit area and time
D. none of the above
Answer» D. none of the above
Discussion
46.

When a body receives radiation in the wavelength range of 0.1 to 100 μm (micrometer), then its temperature
A. increases
B. decreases
C. does not change
D. unpredictable
Answer» B. decreases
Discussion
47.

In which mode, does the heat energy transfer between two bodies when they are separated by some distance and there is no any medium between them?
A. conduction mode of heat transfer
B. convection mode of heat transfer
C. radiation mode of heat transfer
D. heat transfer cannot takes place with above condition
Answer» D. heat transfer cannot takes place with above condition
Discussion
48.

The radiation takes place
A. through molecular communication
B. through vacuum
C. both a. and b.
D. none of the above
Answer» C. both a. and b.
Discussion
49.

The radiant heat emitted by any body travels at the speed
A. less than the speed of light
B. more than the speed of light
C. equals to the speed of light
D. unpredictable
Answer» D. unpredictable
Discussion
50.

The Stefan-Boltzmann law of thermal radiation is applicable for
A. white body
B. gray body
C. black body
D. all of the above
Answer» D. all of the above
Discussion