Check here for the answer.
Using this book
5
Buttons
contain mini
facts: quick information
at your fingertips.
Weird or what?
are
packed with extra weird
or wonderful facts.
Every page is
colour coded
to
show you which
chapter it’s in.
Quick quiz
questions
are
at the bottom
of each page.
Colour coding
identifies each
chapter at
a glance.
Text
gives you
information
about a subject.
Photographs
show you
information
about a subject.
H
a
n
d
s
o
n
Want to try
something for yourself?
Then look at a
“Hands on” tip.
Hands on
tells you
how to get stuck in
and try an experiment
for yourself.
224
225
Some materials are hard and
brittle, while others are flexible.
Some materials are colourful, while
others are transparent. These kinds
of features are called “properties”.
Properties of matter
Brittleness
Somematerials, suchas glass,are
verybrittleandwillbreakwhen
pushedoutof shape.Safety glass is
designed to crack rather thanbreak.
Does it float?
It’s easy to learn about
some properties, such
as the ability to float.
The amount of matter
in a certain volume of
an object is called its
density. Objects and
liquids float on liquids
of a higher density and
sink through liquids
of a lower density.
Is a diamond harder than quartz?
Properties of matter
Materials science
Safety
glass
Yes, a diamond is the hardest mineral of all. It will scratch quartz.
Freezingpoint
is the
temperature atwhich
a liquid becomes a solid.
Plasticity
is howwell
a solid can be reshaped.
Conductivity
is howwell
amaterial lets electricity
or heat travel through it.
Boilingpoint
is the
hottest a liquid can get
before becoming a gas.
What they are...
There are many different
properties of matter.
A smooth flow
Some liquids flow more
easily than others. It depends
on their “stickiness”, or viscosity.
Hot lava from a volcano flows
slowly because it is sticky.
An onion sinks through oil and
water, but floats on syrup.
Syrup sinks belowwater.
A cork floats on oil.
Oil floats onwater.
1
Talc
Hardness
A scientist called Friedrich Mohs created a
scale of ten minerals to compare how hard they
are. Many materials are graded on this scale.
Tensile strength
is how
much amaterial can
stretchwithout breaking.
Flammability
is how
easily and quickly a
substancewill catch fire.
Reflectivity
is howwell
amaterial reflects light.
Water reflectswell.
Malleability
is howwell
a solid can be shaped
without breaking.
Flexibility
is how easily
amaterial can be bent.
Solubility
is howwell
a substancewill dissolve,
such as salt inwater.
Transparency
is how
well amaterialwill let
light pass through it.
Compressibility
Gases can be
squashed, or
compressed, by
squeezing more
into the same
space. This is what
happens when you
pump up a tyre.
A plastic building brick sinks
through oil but floats onwater.
2
Gypsum
3
Calcite
4
Fluorite
5
Apatite
6
Feldspar
7
Quartz
8
Topaz
9
Corundum
10
Diamond
Gas can be compressed
because its particles are far
apart. A bicycle pump pushes
the particles closer together.
Diamond is
the hardest
mineral.
H
a
n
d
s
o
n
Foot pump
Gas particles
A good insulator
Heat cannot easily pass
through some materials.
These are known as
insulators. For example,
aerogel can completely
block the heat of a flame.
But don’t try this at home!
Softest
mineral
Collect some
different pebbles
and put them in order of
hardness. A pebble is harder
than another if it scratches it.
This is how Mohs worked
out his scale.
The lunar
modulewas
nicknamed
the
Eagle
.
Why is there no blue sky on the moon?
280
Men on the moon
281
The universe
Because the moon has no atmosphere.
On 20 July 1969, Neil Armstrong became the first
person to walk on the surface of the moon. He was
joined by Buzz Aldrin. A third astronaut,
Mike Collins, remained in orbit with the
command and service modules.
Men on the moon
What did they do?
Armstrong and Aldrin
spent almost 22 hours
on the moon. About
2.5 hours of this
was spent outside
the
Eagle
, collecting
rock and soil samples,
setting up experiments,
and taking pictures.
Neil
Armstrong
Here comes Earth
Instead of the moon rising,
the astronauts saw
Earth rising over the
moon’s horizon – it
looked four times
bigger than the
moon looks
from Earth.
What was it like?
Buzz Aldrin described
the moon’s surface
as like nothing on
Earth. He said it
consisted of a fine,
talcum-powder-like
dust, strewn with
pebbles and rocks.
We have transport!
Three later
Apollo
missions
each carried a small electric car,
a lunar rover, which allowed the
astronauts to explore away from
the lander. These were left on the
moon when the astronauts left.
Splashdown
The astronauts returned to
Earth in the
Apollo 11
command
module. This fell through the
atmosphere and landed in the
Pacific Ocean. A ringed float
helped to keep it stable.
One lunar rover
reached a top
speed of 22 km/h
(13.5mph).
This dish
antennae
allowed the
astronauts to
send pictures
to Earth.
How did they talk?
There’s no air in space, so
sound has nothing to travel
through. Lunar astronauts
use radio equipment in
their helmets.
W
e
i
r
d
o
r
w
h
a
t
?
The lunar
module computer
on
Apollo 11
had just
71K of memory. Some
calculators can
now store more
than 500K.
W
e
i
r
d
o
r
w
h
a
t
?
Want to know
something surprising?
Then look at a “Weird or
what?” tip.
