CHAPTER 2 (HEAT CONDUCTION EQUATION)

Question 1

is defined as the transfer of thermal energy
from the more energetic particles of a medium to the
adjacent less energetic ones.

Answer 1

heat conduction

Question 2

Conduction can take place in _____
provided that there is no bulk motion involved.

Answer 2

liquids, gases, and solids

Question 3

Heat transfer has direction as well as magnitud making it a

Answer 3

vector quantity

Question 4

The driving force for any form of heat transfer is the

Answer 4

temperature difference

Question 5

T OR F
The larger ΔT, the larger the Heat transfer by conduction

Answer 5

T

Question 6

Specification of the location of point: requires

Answer 6

coordinate system

Question 7

coordinate
system such as the rectangular

Answer 7

x,y,z

Question 8

coordinate system for cylindrical

Answer 8

(r, ϕ, z)

Question 9

coordinate system for sphere

Answer 9

(r, ϕ, θ)

Question 10

Transient heat transfer temperature
varies with

Answer 10

time and position

Question 11

NOTE

Most heat transfer problems encountered in practice are transient in
nature, but they are usually analyzed under some presumed steady
conditions since steady processes are easier to analyze, and they
provide the answers to our questions.

Question 12

not from ppt

the heat energy transferred through the medium is not constant. The heat flow rate keeps changing

Answer 12

transient

Question 13

a line on a map or
chart of the earth’s surface
connecting points having the
same temperature at a given
time or the same mean
temperature for a given period.

Answer 13

isotherm

Question 14

A heat transfer problem is said to be ______ if the temperature in the
medium varies in one direction only and thus heat is transferred in one
direction, and the variation of temperature and thus heat transfer in
other directions are negligible or zero.

Answer 14

1-D

Question 15

1D 2D OR 3D

Heat transfer through the glass of a window

Answer 15

This is 1-D since heat transfer through the glass will occur
predominantly in one direction (the direction normal to the surface
of the glass) and heat transfer in other directions (from one side
edge to the other and from the top edge to the bottom) is
negligible.

Question 16

1D 2D OR 3D

Heat transfer through a hot water pipe

Answer 16

This is 1-D since heat transfer through the pipe occurs predominantly
in the radial direction from the hot water to the ambient, and heat
transfer along the pipe and along the circumference of a cross section
z- and Ø directions) is typically negligible.

Question 17

1D 2D OR 3D
Heat transfer to an egg dropped into boiling water.

Answer 17

Nearly 1-D because of symmetry. Heat will
be transferred to the egg in this case in
the radial direction, that is, along straight lines
passing through the midpoint of the egg

Question 18

The conversion of electrical, nuclear, or chemical
energy into heat (or thermal) energy.

Answer 18

HEAT GENERATION

Question 19

A volumetric phenomenon. That is, it occurs
throughout the body of a medium.

Answer 19

HEAT GENERATION

Question 20

Examples heat generation
1. Heat is generated in the heating coils of an electric
range as a result of the conversion of electrical
energy to heat.
2. Nuclear power plant / Nuclear Reactors

Question 21

The absorption of solar
radiation by water can be
treated as

Answer 21

heat generation

Question 22

The rate of heat generation
may vary with ______ within the medium.

Answer 22

time and
position

Question 23

Most heat transfer problems encountered in practice can be
approximated as being ______

Answer 23

one-dimensional

Question 24

three-dimensional heat conduction through a
rectangular volume element.

steady state called the

Answer 24

Poisson equation

Question 25

three-dimensional heat conduction through a
rectangular volume element.

transient, no heat generation called the

Answer 25

diffusion equation

Question 26

three-dimensional heat conduction through a
rectangular volume element.

steady-state, no heat generation called the

Answer 26

Laplace equation

Question 27

At ______conditions, the entire heat generated in a solid must leave the
solid through its outer surface.

Answer 27

steady

Question 28

The maximum temperature in a
symmetrical solid with uniform
heat generation occurs at its

Answer 28

center