Transient Heat MCQs

Welcome to our comprehensive collection of Multiple Choice Questions (MCQs) on Transient Heat, a fundamental topic in the field of Heat Transfer. Whether you're preparing for competitive exams, honing your problem-solving skills, or simply looking to enhance your abilities in this field, our Transient Heat MCQs are designed to help you grasp the core concepts and excel in solving problems.

In this section, you'll find a wide range of Transient Heat mcq questions that explore various aspects of Transient Heat problems. Each MCQ is crafted to challenge your understanding of Transient Heat principles, enabling you to refine your problem-solving techniques. Whether you're a student aiming to ace Heat Transfer tests, a job seeker preparing for interviews, or someone simply interested in sharpening their skills, our Transient Heat MCQs are your pathway to success in mastering this essential Heat Transfer topic.

Note: Each of the following question comes with multiple answer choices. Select the most appropriate option and test your understanding of Transient Heat. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

So, are you ready to put your Transient Heat knowledge to the test? Let's get started with our carefully curated MCQs!

Transient Heat MCQs | Page 3 of 8

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Q21.
A thermocouple junction in the form of 4 mm radius sphere is to be used to measure the temperature of a gas stream. The junction is initially at 35 degree Celsius and is placed in a gas stream which is at 300 degree Celsius. The thermocouple is removed from the hot gas stream after 10 seconds and kept in still air at 25 degree Celsius with convective coefficient 10 W/m² K. Find out the time constant of the thermocouple. Assume the thermos-physical properties as given below:

h = 37.5 W/m² K

p = 7500 kg/m³

c = 400 J/kg K

a.

6.67 seconds

b.

106.67 seconds

c.

206.67 seconds

d.

306.67 seconds

Discuss
Answer: (b).106.67 seconds
Q22.
What percentage of water an average human body can have?

a.

52%

b.

62%

c.

72%

d.

82%

Discuss
Answer: (c).72%
Q23.
According to lumped system analysis, solid possesses thermal conductivity that is

a.

Infinitely large

b.

Infinitely small

c.

Moderate

d.

50% small

Discuss
Answer: (a).Infinitely large
Q24.
The temperature and rate of heat conduction are undoubtedly dependent on

a.

Time coordinates

b.

Space coordinates

c.

Mass coordinates

d.

Both time and space coordinates

Discuss
Answer: (d).Both time and space coordinates
Q25.
Glass spheres of 2 mm radius and at 500 degree Celsius are to be cooled by exposing them to an air stream at 25 degree Celsius. Find the minimum time required for cooling to a temperature of 60 degree Celsius. Assume the following property values

Density = 2250 kg/m³

Specific heat = 850 J/kg K

Conductivity = 1.5 W/m K

a.

13.78 seconds

b.

14.78 seconds

c.

15.78 seconds

d.

16.78 seconds

Discuss
Answer: (b).14.78 seconds
Q26.
Which is true regarding lumped system analysis?
(i) Conductive resistance = 0

(ii) Convective resistance = 0

(iii) Thermal conductivity = 0

(iv) Thermal conductivity = infinity

Identify the correct statements

a.

1 and 2

b.

1, 2 and 4

c.

1 and 4

d.

2 and 4

Discuss
Answer: (c).1 and 4
Q27.
Which of the following is an example of lump system analysis?

a.

Heating or cooling of fine thermocouple wire due to change in ambient temperature

b.

Heating of an ingot in an furnace

c.

Cooling of bars

d.

Cooling of metal billets in steel works

Discuss
Answer: (a).Heating or cooling of fine thermocouple wire due to change in ambient temperature
Q28.
An average convective heat transfer coefficient for flow of air over a sphere has been measured by observing the temperature-time history of a 12 mm diameter copper sphere (density = 9000 kg/m³ and c = 0.4 k J/kg K) exposed to air at 30 degree Celsius. The temperature of the sphere was measured by two thermocouples one located at the center and the other near the surface. The initial temperature of the ball was 75 degree Celsius and it decreased by 10 degree Celsius in 1.2 minutes. Find the heat transfer coefficient

a.

27.46 W/m² K

b.

21.76 W/m² K

c.

29.37 W/m² K

d.

25.13 W/m² K

Discuss
Answer: (d).25.13 W/m² K
Q29.
Transient condition means

a.

Conduction when temperature at a point varies with time

b.

Very little heat transfer

c.

Heat transfer with a very little temperature difference

d.

Heat transfer for a short time

Discuss
Answer: (a).Conduction when temperature at a point varies with time
Q30.
Which of the following is not correct in a transient flow process?

a.

The state of matter inside the control volume varies with time

b.

There can be work and heat interactions across the control volume

c.

There is no accumulation of energy inside the control volume

d.

The rate of inflow and outflow of mass are different

Discuss
Answer: (c).There is no accumulation of energy inside the control volume
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