668 20 5MB
English Pages  Year 1964
A Snaggi Littletoof Short Story READ IT BECAUSE Get a glimpse into the inner workings of grot politics in an ancient ae
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Robert de Niro and Al Pacino have acted opposite each other once, and that was in Heat, Michael Mann’s operatic 1995 hei
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This textbook presents the classical topics of conduction heat transfer and extends the coverage to include chapters on
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Учебное пособие «Теплоэнергетика. Heat generation and distribution» предназначено для практических занятий по английском
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The book presents a detailed discussion of nanomaterials, nanofluids and application of nanofluids as a coolant to reduc
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Free Convective Heat Transfer is a thorough survey of various kinds of free-convective flows and heat transfer. Referenc
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Digitized by the Internet Archive in
The "Reason Why" Books
HEAT Irving and Ruth Adler
The John Day Company
The "Reason Why" Books by Irving and Ruth Adler AIR
ATOMS AND MOLECULES COAL COMMUNICATION EVOLUTION FIBERS
HEAT HOUSES INSECTS AND PLANTS IRRIGATION: CHANGING DESERTS TO GARDENS
LEARNING ABOUT STEEL THROUGH THE STORY OF A NAIL MACHINES
MAGNETS NUMBERS OLD AND NEW NUMERALS: NEW DRESSES FOR OLD NUMBERS OCEANS RIVERS SETS
SHADOWS STORMS TASTE, TOUCH AND SMELL THE EARTHS CRUST THINGS THAT SPIN TREE PRODUCTS WHY? A BOOK OF REASONS WHY AND HOW? A SECOND BOOK OF REASONS YOUR EARS YOUR EYES
© 1964 by Irving and Ruth Adler must not be reproany form without permission. Published by The John Dav ir ' " stlV(,t New York 36 x Y an(1 l' lf 'lL si muTt a n e orT?rC'^P^i a d a by Longmans Canada Limited, Toronto.
All rights reserved. This hook, or parts thereof,
Congress Catalogue Card Number: 64-13788
THE UNITED STATES OF AMERICA Third
Contents Level of Heat and
Popping Milk Cartons
The Thermometer The Dance of the Molecules Burning: Molecules Take New Motion Makes Heat Heat Makes Motion Heat Makes Light Electricity
10 12 Partners
The First Rule of Energy: Energy The Second Rule of Energy
Taking Pictures Without Light
Gas and Plasma Measuring High Temperatures The Highest Man-made Temperatures Taking the Temperatures of the Sun and the The Heat of the Earth Heat and Life The Fire That Burns Inside You Heating Our Houses Refrigerators and Air Conditioners Taking Heat Away
Engines with the Fire Inside
30 32 Stars
33 34 36 38
In places where
houses to keep ourselves warm. ourselves T~l
Clothing keeps in the heat of our bodies.
heat our food to cook
We heat metals and glass to make them Then we can work them and shape
We make run.
into useful things.
use the heat of burning fuels to airplanes,
use the heat of burning fuels to
carry rockets into space.
We can even use
heat to take pictures.
The heat alive.
of burning food keeps animals
The h n.at
of the sun
and gives us bright daylight. Plants and animals cannot live without the heat and light of the sun.
of the stars
though they are
billions of miles
How can we tell that something is hot? How can we tell how hot the air is? How can
hot the sun
the hottest thing on the earth? In this book on heat
answers to these questions.
shall find the
from a higher place
Level of Heat and
comes from a hot-water faucet
... to a
spoon that you take from the kitchen
feels cool to
you put the spoon
a glass of hot water, the spoon begins to get hot. It gets hotter
and hotter until
got hot because
The spoon water and went into
as hot as the water.
heat behaves like a liquid. place to a lower place.
level of heat in a hot object
level of the liquid in the higher place.
same way. There
the level of
the liquid in the lower place becomes the
flow in the
from a higher
heat in every object. higher than
in a cool
object. If a hot object touches a cool object, heat flows
from the hot cool object,
where the heat
where the heat
high, to the
the two objects have the same heat level. 6
level of heat in
level of heat in
in the object are
and a quart
an object and the amount of heat
not the same. Suppose you
with hot water from a
perature, or level of heat, in both jars
a pint jar
every pint of water at that temperature has a certain
of heat in
But a quart of water
much as a pint. So the quart much heat in it as the pint jar. The amount ories
of heat in something
water has twice as
KAL-o-rees ) --£
the temperature of the
then the level of heat
the same, but the
amount of heat is different. The water in the quart as much heat in it as the water in the pint jar.
Broken Jars Every housewife knows that she must never pour a very hot liquid into a cold glass jar. To do so might
Heat flows from the hot liquid
makes the glass
glass try to take
A very hot
expand so quickly that the
Most things expand
warmer. At the same time,
into the cold
glass will crack.
grow warmer. Engineers
they build concrete highways in sections
with spaces between them. The spaces give the concrete sections
there were no spaces
expand during hot weather.
mer sun would make Railroad
sections, the hot
highway buckle and
are laid with spaces
cover of the carton will
pop open by
Popping Milk Cartons
Take a and
partly filled milk carton out of the refrigerator
on the kitchen counter. After a
cover of the carton will pop open
Because the carton is
above the milk. The
milk. It also presses against the sides
with milk, there
and the top
air presses against
(PRESH-er) on the
The warm kitchen makes the wanner. As the air gets warmer
against the of the
inside the carton
presses harder and
harder against the sides and top of the carton. So the pressure of the air on the inside of the carton increases. Finally the pressure
so great that
makes the cover
inside the milk carton
a gas like air
shows that the
presses against the
most things expand as they grow warm-
er gives us
of measuring temperature.
MOM-eh-ter). Some thermometers use expanding to
use expanding gases.
The weather thermometer
-LThe weather thermometer
of a thin tube of
bulb at the other end. The glass bulb of the ther-
sealed at one end. It
joined to a small
with a liquid. Alcohol (AL-ka-hall)
usually used for cheap weather thermometers. hol
colored red or blue to
easy to seel
weather thermometers and doctors' thermometers are
with a liquid metal called mercury
may be mounted on a scale with numbers Or the numbered scale may be printed right on the
the temperature near a thermometer increases,
the liquid inside the thermometer expands. There
one way that the liquid can take up more space.
up more space by climbing up the tube of the thermometer. The warmer it becomes, the more the liquid expands.
in the glass tube.
the liquid expands, the higher
The temperature 10
number on the
which the liquid reaches.
scales are usually
thermometers. Both scales are based on the temperature at
which water freezes and changes
perature at which
and the tem-
steam or water
vapor (VAY-per). The scale used in Great Britain and in the scale.
the Fahrenheit (FARR-en-hite)
the Fahrenheit scale water freezes at 32 de-
grees and boils at 212 degrees. There are 180 degrees be-
tween the freezing point and the boiling point of water. Because
number system based on
ter to use a scale that has
100 degrees between the freez-
ing point and the boiling point of water.
with a scale like this
scientific experiments. It
most of the countries of the world. This
It is also
called the Centigrade (SEN-tih-grade) called the Celsius (SELL-see-us)
thermometer, after the
Centigrade or Celsius scale 10
Fahrenheit scale 11
The Dance of the Molecules Everything in the world (
MOLL-eh-kules ) The smallest .
cule of water.
The smallest bit of salt
Molecules are so small that
water were put
in a row,
Molecules are moving
a molecule of
forty million molecules of
they would take up only an inch. all
cules are held in place
the time. In solids, the mole-
cules of a solid are not free to
So the mole-
wander but they can
and swing back and forth or vibrate (VY-brate). In
They can wander but they are kept close to each other by the electrical forces. In gases, the molecules are separated by big spaces and move about freely. You can see the movement of the molecules of a liquid liquids, the molecules are not held in place.
with the help of a microscope. First sprinkle a fine powder in some water. Then take a drop of water with powder in
under the microscope. The
They move this way and that. The bits of powder move because molecules of water keep bumping into them and push them around. If the water
because heating the water has
the molecules of water
powder move even
heated, the bits of
fact that molecules are
the time helps
the motion of
fact that molecules are
a spoon gets hot
in the hot
the time ex-
put into a glass of
water are moving
faster than the molecules in the cool spoon.
water touches the spoon, the fast-moving molecules of
water give the slow-moving spoon molecules next to
them a hard push. The push makes the spoon molecules
These faster-moving spoon molecules,
look under a
molecule as microscope
The faster-moving water molecules make the spoon molecules move faster. So the spoon gets hot.
spoon molecules that they
push. In this
into a hard
the molecules in the spoon
and the spoon gets warmer. At the same
when water molecules bump
the water molecules slow down. So the water gets cooler,
molecules are moving more slowly.
spoon molecules are moving as cules, the
fast as the
tions. So, as
the time ex-
make bigger and bigger
molecules begin to
more and more. Because up more
faster. In a solid
spoon and water have the same temperature.
fact that molecules are
As a body
molecules swing out
of these wider swings, the
fact that molecules are
why, the warmer
on the walls of
against the walls of the container.
of air in a
warmer, the molecules of
inside the container gets
milk container are moving around very
the time ex-
the walls of the container harder and
they hit the walls of the container harder and more often, their pressure
on the walls
the air becomes warmer,
pressure on the walls of the
sure on the inside of the
air inside a tire tire
warmer. Then the pres-
Burning: Molecules Take
New Partners and wood
to give us
heat for cooking and for heating our homes. Cooking gas, oil,
and wood are
fuels to burn, they
oxygen (OX-i-jen). Fuels usually get the oxygen they
burning from the
one-fifth of the air
The molecules of cooking gas, oil, coal and wood are made up of atoms of carbon C AR-bun and hydrogen Carbon and hydrogen are chemical eleHY-dro-jen ments. There are 102 different chemical elements. Atoms (
of chemical elements
to build molecules.
atoms of hydrogen and one atom of oxygen join to
make one molecule of water.
When a fuel burns, a chemical change takes place. The chemical elements in the fuel join with oxygen to change the fuel into something else.
burn, their carbon atoms join with atoms of oxygen in the air to
of a gas called carbon dioxide
A hydrogen atom
An oxygen atom 16
(CAR-bun dy-OX-ide). Their hydrogen atoms join with oxygen in the air to make molecules of water vapor. These chemical changes take place
When these chemical off.
in the flame.
changes take place, heat
have found that every time two atoms of hydrogen and
one atom of oxygen water, the
join together to
a molecule of
The chemical changes in which heat is given be made to work the other way around. For this pen, heat must be put
make water vapor entists
Two atoms molecule
hydrogen and oxygen.
water into hydrogen and oxygen
So heat has to be supplied to
have found that the amount of heat that
of heat given off
when hydrogen and
fonn water vapor.
hydrogen and one atom
Rubbing your hands together makes them warm.
Motion Makes Heat
Whenever you fact that its
match, you make use of the
motion makes heat. To
something rough. The
of chemicals that
match, you rub
tip of a
hot enough to burst into flame.
There are many other things you do that show that
warm hot when pump hot
motion makes heat. You rub your hands together to
in the wintertime.
You make a
You make the barrel of a tire the piston in and out. You make a
when you pull hot when you drill
a hole in wood.
Why do these motions make heat? The motion
bing your hands makes the molecules in your skin vibrate harder. But the heat of a cules.
the motion of
So when your skin molecules vibrate harder, your
hands become warmer. The motions of drilling, hammering and pulling a piston in and out all make molecules
made warmer by 18
the nail and the
Heat Makes Motion
We use the fact that heat makes motion to make
mobiles, ships and airplanes run and to carry rockets into space. In
of these cases,
a gas very hot.
a gas very hot increases the pressure of the gas.
the great pressure of the gas gives the push that
makes the thing move.
machine that changed heat
the steam engine. In a steam engine a burning fuel
used to heat a boiler of water. turns to steam.
back and is
the water boils
pressure of the steam pushes a piston
forth. This back-and-forth
motion of the piston
the motion of the steam engine that
The earliest locomotives were steam used wood or coal as fuel.
pages 44, 45 and 46
gines that change heat into motion.
This steam locomotive
about other en-
Heat Makes Light
When wood burns, it gives out a warm reddish-orange light. A burning gas flame glows with a pale blue light. Burning all
out a bright yellow
examples of another fact about heat.
an empty iron pan
time, the light.
begins to give out
on a hot stove
so hot that
say that the pan
for a long
glows with a reddish
volcano on an island north of
lava inside Stromboli, a
up the sky
night with a red glow.
Some things are so hot that they give out a white light. Then we say they are "white-hot." The sun and the stars are great masses of hot gases. They are so hot that they give out a bright white light that
use electric irons, electric toasters and electric
even cook and heat our homes with use electricity to
electricity. All of these things
heat. In all of
them there are metal
allowed to flow. The flowing elec-
You can see the red stove and an electric
current makes the coils red-hot.
of the hot coils of an electric
glows with a white
on for a while,
oxygen inside ah
electric light bulb.
turned on, an electric current begins to
flow through a fine wire inside that
After the bulb has been
becomes too hot
electric light bulb.
docs not burn up even though 21
gets so hot
So the wire inside
The First Rule of Energy: Energy Is Never Lost There
energy stored in your muscles. The energy
makes your muscles do work, There
drive a nail into a piece of wood.
energy in an electric current. The energy of an
can ring a
up a room
The energy in your muscles, the energy
swinging a hammer.
energy in a swinging hammer. The energy of a
or heat a
in a swing-
the energy in an electric current are
different forms of energy. Sound, light
and heat are forms
of energy, too.
forms are related, because energy keeps changing from
one form to another. Heat, as one of the forms of energy, can be changed into every other form. In a steam engine, the heat of a burning fuel tion.
At an is
into energy of
plant, the heat of a
into electrical energy.
Other forms of energy can be changed into heat. The energy of motion of a swinging heat
hammer hits the heat when an
coils of a stove.
Although the form of energy keeps changing, the
of energy never changes.
been changed into
energy of motion has been
hits a nail,
an equal amount of heat energy. Scientists
call this rule that
when you swing a hammer. It lias an equal amount of energy of motion. lost
the law of conserva-
energy (KON-sir-VAY-shun). To conserve means
The energy stored in
an equal amount of energy of motion
of heat energy.
an equal amount
The Second Rule of Energy
you hammer a
nail into a piece of
change the energy of motion of the hammer into energy of heat.
page 13 you learned that heat
of the molecules.
of billions of
when you swing a hammer, its molecules are moving. Then how is the motion of a swinging hammer different from the motion we call heat? molecules. So
When you swing a hammer,
of the molecules of the
hammer swing together. They all move in the same direction. Thev all move toward the nail. All of the molecules in the hammer move at the same speed. They all move with the speed of your swing. The motion of the molecules in the swinging
the nail, the orderly motion disappears.
Molecules in the
by the blow. They begin
to vibrate wildly,
directions at different speeds. Their motion
The motion swinging
They all move at the same speed in the same direction.
orderly or scattered. This disorderly motion of the molecules
what makes the hammer and the heat
sometimes called disorderly or
rule of energy taught us that energy
hit the nail, all of the
of the energy of heat can
push the hammer up again? According
the second rule of energy, this this rule,
energy of mo-
into energy of heat. Is there
energy of motion? Can the heat in the nail
only changed from one form to another.
more and more
things around us
of the orderly motion of the
being changed into heat or disorderly
motion. Because of this rule, scientists think the motions of the sun, the planets little
nail are given
So the hammer and
hits the nail,
nail get hot.
Taking Pictures Without Light
you take a picture with your camera, you make
sure that there
you are taking a picture of
Light rays from the object
strike the film inside
camera. The light makes a chemical change in the
The chemical change
dark areas light
in the film
and dark areas on
the negative from which a
black and white printed picture It is
The It was
possible to take pictures without light, too.
picture on this page of a car
in the dark.
taken with the help of heat rays.
They are visible VIZ-ibble ) It gives out heat rays, too. You cannot see the heat rays. They are invisible ( in-VIZ-ibble Heat rays and light rays are both caused by vibrations inside the atoms and molecules of an object. They are both radiations RAY-dee-AY-shuns ) caused by these vibralight rays. (
see the light rays.
the vibrations that
rays are slower than
Infrared rays are used for taking pictures without light.
how. Different parts of the car give out different
amounts of heat tion that
and changes them
matches the shape of the
era receives these rays signals. It
a strong signal
a pattern of heat radia-
parts of the car nals that
where the heat rays are
where the heat rays are
the pattern of heat rays from different
into a pattern of electrical sig-
matches the shape of the
into a pattern of
strong rays of light. This pattern of light rays
strikes the film inside the
matches the shape of the
camera, making a picture that
in a liquid state
kitchen faucet. it
comes the gas we
Gas and Plasma
comes out of your
steam or water vapor.
are used to thinking of water as being in three
you may have the idea that iron
the idea, too, that air
always a gas. Both of
these ideas are wrong. Iron and air can be in other states, too,
If air is it
their temperatures. If iron
about 1500 degrees Celsius,
becomes a liquid,
140 degrees below zero Celsius,
In a solid, the molecules are held in place forces.
When a solid is heated,
molecules vibrate more
and more. After a while, the molecules vibrate
that the electrical forces aren't strong
any more. Then the molecules are free to
move around. The
and becomes a liquid that
Finally, the molecules are so far apart
from each other
that the electrical forces are too all.
open and is
atoms separate. At
they hit each other they this
hydrogen and oxygen atoms. At
20,000 degrees Celsius even the atoms
heated to about 4000 degrees Celsius,
happens the liquid evaporates (ee-VAP-
and becomes a
the gas becomes a plasma
split into pieces.
Melted iron being poured into a converter 29
Measuring High Temperatures
can measure the temperature of boiling water by
putting a thermometer into the container of water.
cannot measure the temperature at which iron melts by putting a thermometer into the liquid iron because the
thermometer would melt,
Nor can we use ordinary
thermometers for measuring the temperatures of plasmas.
measure very high tem-
called a hot body.
tures of very hot bodies can
tance. This can radiation.
be measured from a
be done by catching and measuring their
A tool for doing this is called a pyrometer
One kind hotter a
pyrometer makes use of the fact that the is,
radiates. This kind
of pyrometer measures temperature
by measuring the
energy in the rays
receives from the hot body. It
changes the energy
receives into an electric current.
of current flowing through the
a clue to the temperature of the hot body.
Another kind of pyrometer uses the out by a very hot body to measure is
done by comparing the
the light given out
from the hot body with
by the glowing wire 30
visible light sent
of a special kind
of electric light bulb.
The temperature and
the glowing wire are changed by changing the amount of current flowing through til
the glowing wire and the visible light from the hot
body have the same
clue to the temperature of the very hot body. eter like this
of a volcano.
The temperature of the lava in the mouth of this volcano was measured with a pyrometer. 31
perature of the lava was 1200 degrees Celsius.
measure the temperature
of the hot
gases that surround the sun is about 1 million degrees.
temperature inside the sun is
The temperature on the surface of the sun is about 6000 degrees.
The Highest Man-made Temperatures Scientists ries that
have made temperatures
are higher than the temperature on the surface
of the hottest star.
in their laborato-
highest laboratory temperature
inside a shock tube.
shock tube uses a
gas under very high pressure to push against a second
gas under low pressure. in the
second gas. In a shock wave, the molecules of gas
depends on how to see
The push produces
Since the temperature of a body
molecules are moving,
the second gas gets very hot. Temperatures 32
more than 500,000 degrees Celsius have been made
man-made temperature is the temperahydrogen bomb when it explodes. The tem-
ture inside a
about 100 million degrees Celsius. That
why hydrogen bombs can do
Taking the Temperatures of the Sun and the Stars
93 million miles away. The nearest
billions of miles
away. Even though they are so far away,
their surface temperatures
kind of pyrometer
can be measured.
used for doing
This kind of
pyrometer has a telescope that catches radiation from the sun or the
then measures temperature by
measuring the amount of energy hottest stars
in the radiation.
have a surface temperature of about 80,000
degrees Celsius. The surface of the sun Its
The to the
only about 6000 degrees Calsius.
receive from the sun or a star are a clue
temperature inside the sun or the
omers have figured out that the temperature sun
about 20 million degrees Celsius. The temperature
inside the hottest stars
about 2 33
of the Earth
The highest air temperature ever measured on the surface of the earth was at a place in northern Africa. It once was 136 degrees Fahrenheit there. The lowest air temperature ever measured on the surface of the earth
was near the South
once was 126 degrees below
zero there. Temperatures inside the earth are higher.
inside of the earth gets
at the center of the earth
3000 degrees Celsius.
as high as
are higher even than the temperature of
heat in two ways.
heat from certain rocks inside the earth.
rocks, called radioactive rocks, contain elements
radium and uranium. The radium and uranium
atoms break up and send out energy. This energy warms
inside of the earth also gets
from the pressure of rocks near the surface on rocks deep
The pressure on the rocks deep inside The great pressure makes them very hot.
inside the earth. is
The surface of the earth The most important way earth gets
heat in two ways, too.
which the surface of the
from the sun. Some of the heat of
the earth's surface comes from the inside, too.
to the surface
from inside the earth
as heat rises in a room.
around the earth, the
the sun and the plan-
very low. Since
heat flows from a higher level to a lower level, the earth is
surface heat into space
However, the surface heat that the earth is
loses into space
balanced by the heat the earth receives from the sun
and by the heat that comes from the
The surface losing
of the earth of
heat from the sun and heat that rises up from the inside
the earth does not cool
... but the surface
to the surface of the earth
earth does not cool off .35
Heat and Life Nothing can too
without heat. Nothing can
heat either. Most things can live only within
a narrow band of temperatures. Nothing can live at a
temperature lower than 100 degrees below zero Fahrenheit.
live at a
temperature higher than 225
degrees above zero Fahrenheit. Most things live in the
even narrower band of temperatures between 32 degrees
and 122 degrees Fahrenheit. At lower temperatures,
At higher temperatures,
would be cooked
long time ago people did not live in houses or wear
clothing. So they
people began to wear
clothing and learned
heat their houses, they could live almost anywhere on the earth.
they can even
heated rockets and
into space that
colder than any
place on the earth.
warm. But there are some
animals that can even live in the Far North at freezing temperatures. These animals are kept coats of fur or feathers.
of these animals cannot get along
gets very cold
to places that are
So they migrate
birds migrate in the wintertime. There are flies
that migrate, too.
Some animals can they
an animal hibernates,
body temperature in its shelter all
in a ball
ve r y
There are a few animals that can cold or where
get along (
very hot without any
polar codfish swims in the icy polar seas at 29 degrees
a sea plant that lives in hot pools of
temperature of 190 degrees Fahrenheit.
A hibernating ground 17
The Fire That Burns Inside You Your body There the
different kinds of cells.
that burns inside every cell.
the food you eat.
for the fire
the air you breathe.
that burns inside
you has no flame. Although
no flame, the chemical changes that take place
when food burns
changes that take place eat has carbon
cells are a lot like
The food you
When the food burns,
make water vapor. The carbon joins with oxygen to make carbon dioxide. The water vapor and carbon dioxide leave your body when you breathe out. The fire that burns inside you makes the heat that the hydrogen joins with oxygen to
keeps your body warm.
makes the energy
makes your muscles move.
need a sceady supply of food
day long, you would
in order to stay healthy.
There are muscles inside you that are working
The muscles of your heart are working all the time to make your heart beat. The muscles of your diaphragm (DY-a-fram) are working all the time to make you breathe. Your body is kept warm all the time. It is kept time.
about 98.6 degrees Fahrenheit by a heat regulator
side your brain. So even
when you 38
you are burn-
keep your body going and
of food a person must eat
So a grown-up must eat more than a
must eat more than
depends on child.
who has a broad body must eat more than a perwho has a narrow body. An average-sized man must
more than an average-sized woman.
The amount does.
a person eat
of food a person eats
depends on what he
does hard work must eat more than
sitting at a desk.
a radio announcer.
less active as
they grow older. So old peo-
ple should eat less than they ate
they were young.
who eat more food than their bodies burn get fat. That is why many people get fat as they grow older. People
The amount sex,
of food a person should eat
body build and the kind
work he does. 39
Heating Our Houses In order to heat a room, heat from a hot
spread through the room. This happens in three ways.
hot body gives
off infrared rays.
from the hot body
of the heat
to cooler bodies
of spreading heat
The sun heats the earth by radiation. A hot body also warms the air around it. Some of the warm air spreads through the room by the motion of the molecules of air. This way of spreading heat is called Conduction of heat is conduction kon-DUCK-shun
warm air spreads through the room when warm air rise and flow away from the hot
body. Currents of cool
hot body to take the place of the
toward the This
Convection spreads the heat more quickly than conduction does.
used stoves and fireplaces to heat their
fireplaces could heat only
Modern houses have
central heating systems.
heating system has a furnace in which a fuel like
cooking gas or coal
burned. The furnace
the basement of the house. Heat produced ing fuel
by the burn-
carried to other rooms of the house
There are several ways of doing
In a hot-air heating system, air
I* ^ ^
* + *I nace.
in the fur-
fan blows the hot air through large pipes called
The ducts lead Each room has
the hot air to openings called regis-
a hot-air register placed near the
has a cold-air register near the ceiling. Other
ducts carry cold air back to the furnace to again.
hot-air heating system heats mostly
In a hot-water heating system, water
pipes to radiators in each room.
passes from the
the furnace until
The steam Hows through
the pipes to the radiators. Steam radiators the
by both conduction and convection.
In a steam system, water it
motor pushes the hot water through
radiators to the air
that hot-water radiators do. 41
and Air Conditioners: Taking Heat Away
of an electric current to
taken away from some-
page 29 you learned that
refrigerator use the energy of an electric current to
take heat away.
electric toaster use the
begins to evaporate or change to a gas or va-
changing a liquid to a
when a liquid evaporates, the molecules that leave it to become a vapor are taking heat out of the liquid all the time. The liquid gets the heat it needs to make it evaporate from its surroundings. That is why you wet your you cool
skin to help
your skin evaporates, cools
things in the
on a hot day. As the water on
takes heat out of your skin
Air conditioners and refrigerators cool
Cooling coils inside the refrigerator
Outside coils on the back of the refrigerator refrigerator
a refrigerator works.
liquid that evap-
orates easily flows through small pipes, or coils, inside
called a refrigerant
FRIJ-er-aut). As the refrigerant evaporates it
gets the heat
needs by taking heat
out of the air and the food in the refrigerator. In
the inside of the refrigerator gets very cold.
More and more coils
of the refrigerant evaporates in the
and keeps cooling the
inside of the refrigerator.
the refrigerant evaporates, the vapor flows through the
compressor (com-PRESS-er). The compress-
coils to the
run by an electric motor. The job of the compressor
and squeeze the vapor. Pressing and squeez-
ing the vapor turns frigerant liquid
into a liquid again.
on the outside of the
The warmed-up the
the outside then takes heat out of the frigerant, cooling
the cooled liquid refriger-
ant flows back into the coils inside the refrigerator, where it
evaporates again. In this
out of the food and
the heat to the outside
the refrigerant takes heat
the refrigerator and carries
conditioner uses a refrigerant to take heat out
of the air inside a house'
and carry the heat
outside the house. 43
to the air
Engines with the Fire Inside
In the steam engine you read about on page 21, the fire
that heats the boiler of water
in a separate firebox
outside the engine. There are other engines in which the fire is
inside the engine
car or an airplane, the
gasoline engine of a
engine of an airplane and the
rocket engine of a spaceship are
A gasoline engine has one or more cylinders ders) in which the burning takes place. six cylinders.
the cylinder (1).
the spark plug,
into a small space at
one end of the cylinder (2). Then an mixture.
In a gasoline engine, a mixture of gasoline
presses the mixture
allowed to pass through the mixture on
Inside the cylinder of a gasoline engine
The burning mixture produces hot gases at high pressure. The great pressure of the burnt gases pushes sion.
the piston back to the other end of the cylinder
again, pushing the burnt gases
out of the cylinder (4). After the burnt gases have been
out, the cylinder
reach For a new explosion. In
a car, the up-and-down motion of the piston
turn gears that turn the wheels of the car. In a gasoline engine, hot gases are produced at high
pressure in order to push pistons. tons
used to turn the wheels of a car or the propeller
of an airplane. In a jet plane, the push of the hot gases
used to push the plane forward without the help of tons.
the engine of a
enters the engine at
plane works. Air air
very hot. Then gasoline or kerosene
into the hot
the spray hits the hot.
Fuel burns here
Diagram of a rocket
the spray starts to burn. Burning pro-
duces hot gases at high pressure. The pressure forces the burnt gases out through a narrow opening at the back of the engine.
against the plane
gases pushed out in this
burnt gases pass through a turbine (TUR-
a wheel with
burnt gases push against the
The turning turbine makes the compressor work. When the compressor works, more fresh air comes turbine turn.
into the jet engine to
inside the jet engine
rocket engine works like a
engine, except that
drawn in from the outside. Rockets travel space where there is little or no air. They do
doesn't use air
high up in
not get oxygen from the space around them. So rockets take along their rocket needs
supply of oxygen. The oxygen a
carried in a tank.
used because then a
oxygen can be compressed into a 46
The tank has
liquid lot of
of heat in something. 252 calorics arc needed
temperature of one pound of water one
to raise the
by the motion of the molecules. Convection (kon-VECK-shun)
when warm air rises and cool air sinks to take Degree — The unit for measuring temperature. Evaporate
ee- VAP-or-ate )
change a liquid
temperature Infrared rays
heat. It curls
in a ball
falls. It rests in its
an animal does to
smallest bit of
against the walls of
— How its
very high temperatures
hard something pushes
at a distance.
something. Vibrate (VY-brate)
move back and IT
About the Authors and Ruth Adler have written more than fifty books about science and mathematics. Dr. Adler has been an instructor in mathematics at Columbia University and at Bennington College, and was formerly head of the mathematics department of a New York Irving
City high school.
mathematics, science, and art in schools in the
York area, recently also taught dition to
Bennington. In ad-
working with her husband writing
she drew the illustrations.
Books by Irving Adler alone and books by him collaboration with Ruth Adler have been printed 77 different foreign editions,
languages and in
9 paperback editions.
The Adlers now
live in the
country in Shaftsbury
Township, near Bennington, Vermont.
PHOTOGRAPH CREDIT Pages 26 and 27
are excellent"— New York Herald Tribune
The best of the matter is
One can -be scientific
and Ruth Adler
with authors like the Adlers, their
certain that not only
the exposition clear and logical, but that the
Horn Book Magazine
matters presented are correct and up-to-date— The
THINGS THAT SPIN "A
somewhat complex subject handled with
— The Horn Book Magazine
"A helpful and stimulating book."
THE STORY OF A NAIL 'Presenting a truly excellent account of the historical development of the steel industry. Clear, well-labelled drawings accompany the simple and meaningful text;
understood explanation of the causes and uses of shadows."
NUMBERS OLD AND NEW "A fascinating book
for the student interested in mathematics."
—American Library Association "Exceptional book about
how we came
—Child Study Association
Book of Reasons
"This takes the kinds of questions continually asked by children in 2nd-3rd-4th grades and answers them, so that each topic is complete in itself, within the limitations of the age level and scope. I'd suggest that it be given to a child with an inquiring mind and acquisitive instinct for collecting unrelated facts." —Virginia Kirkus
RIVERS simple "Contains a wealth of information, and the illustrations add clarification enough for third-graders and informative enough for fifth-graders. Recommended." —Library Journal .
OCEANS AIR "These
fine additions to the series are well written
Schools and public libraries will find
interrelation of plants
insects, for the
middle grades. Attractive and useful
-The Horn Book Magazine