162
Unit Fifteen
NUCLEAR PHYSICS
READING PASSAGE
Explaining fission and fusion
In both fission and fusion, unstable nuclei have become more stable. Energy is released.
In order to explain
these processes
, we need to be able to say where this energy comes from.
One answer lies in the origins of the nuclei we are considering. Take, for example,
uranium. The earth’s crust contains uranium. In some places,
it
is sufficiently
concentrated to make it worth while extracting it for use as the fuel in fission reactors.
This uranium has been part of the Earth since it was formed, 4500 million years ago.
The Earth formed a swirling cloud of dust and gas, at the same time that the Sun itself
was forming.
These materials
condensed under the force of gravitational attraction. But
where did they come from in the first place?
It
is believed that heavy elements (such as
uranium) were formed in a supernova. At some time in the distance past, an aging star
collapsed and then blew itself apart in an explosion of awesome scale. At the very high
temperatures that resulted, there was sufficient energy available for light nuclei to fuse to
form the heaviest nuclei, which we now find if we dig in the Earth’s crust. It is this energy,
from an ancient stellar explosion, that is released when a large nucleus undergoes fission.
We can extend this explanation by asking: How can we calculate the amount of energy
released in fission or fusion? To find the solution to
this

So we have put energy in to the system to pull the nucleus apart. Where has this energy gone?
At the same time, we have the mystery of the appearing mass. There is more mass when
we have pulled the nucleons apart than when they are bound together.
You probably already know that these two problems, disappearing energy and appearing
mass, can be solved together. We say that ‘energy has turned to mass’. If we let the separate
protons and neutrons recombine to make a
C
12
6
nucleus, the extra mass will disappear and the
missing energy will be released. This mass-energy conversion explains where the energy
comes from in a nuclear fusion.
A better way to express this is to treat mass and energy as aspects of the same thing.
Rather than having separate laws of conservation of mass and energy, we combine these two.
The total amount of mass and energy together in a system is constant. There may be
conversions from one to the other, but the total amount of mass plus energy remains constant.
(
From

Basic Physics 1 and 2
by David Sang)
READING COMPREHENSION
Exercise 1:
Answer the following questions by referring to the reading passage

1.
What happens in both processes of fission and fusion?
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………

…………………………………………………………………………………………
…………………………………………………………………………
7.
What exactly explains where the energy released in a nuclear fusion comes from?
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………
8.
If we combine the two separate laws of conservation of mass and energy, what name
do you think would be given to the common law?
…………………………………………………………………………………………
…………………………………………………………………………………………
…………………………………………………………………………
Exercise 2:
Contextual reference
(
dealing with words in
bold
type one by one
)
1.
‘
These processes’
in line 2 refers to
a.

the processes of fusion and fission
b.

the process of releasing energy

none of the above

4. ‘it’
in line 10 refers to
a.

the force of gravitational attraction
b.

the first place165
c.

nothing

5. ‘this’
in line 18 refers to
a.

the explanation
b.

the calculation of the amount of energy
c.

fission or fusion

6.

‘
these’
in line 31 refers to
a.

nucleons
b.

nuclear forces

c.

both of the above

Exercise 3:
Decide whether each of the following sentences is true or false. Write (T) for the
true ones, (F) for the false ones and (N) for the ones with no information to justify

1.

………….Energy is released in both fusion and fission and we call it extra energy.
2.

………….Without uranium, the earth could not have formed.
3.

………….Uranium was first discovered 4.500 years ago.
4.

………….Uranium has the heaviest nuclei of all elements,

equivalent sentence. The following two are the common ones.
1. but
and (
al)though
Example
:
You can write:
Although uranium was formed at the same time as the formation of the earth, it is not the
main part of the earth.
(Uranium is not the main part of the earth (al) though formed at the same time as the
formation of the earth)
Or
: Uranium was formed at the same time as the formation of the earth
, but
it is not the
main part of the earth.
You can not write
:
Though
uranium was formed at the same time as the formation of the
earth,
but
it is not the main part of the earth.
In this case, if you replace
but
with
still
or
yet,
you may have the sentence that sounds

: in the open air, or outside
roughly
: violently, briefly, or approximately
2.

flat:
level and horizontal
flatly:
frankly
3.

free
: without
freely
: liberally
4.

late:
after the usual or normal time
lately
: recently
5.

wide:
large and broad in size
widely
:broadly, generally
6.

near:

In 1932, two of “papa” Rutherford’s “boys” John Cockroft and Earnest Walton, managed
to build a device to accelerate protons. It produced only 100.000 volts or so.
…………………………………………………………………………………...……
……………………………………………………………………………....
5.

The arrangement of electrons to make the bonds releases 4.1 electron volts energy.
The splitting (or fission) of one uranium atom’s nucleus would release some 2000
million electrons volt of energy.

168
…………………………………………………………………………………..……
……………………………………………………………………………..….………
………………………………………………………………………...
6.

Uranium-235 nucleus fissions most easily by absorbing a slow neutron. It can also
fission (with a lower probability) as a result of a strike by a fast neutron.
…………………………………………………………………………………..……
…………………………………………………………………………........
7.

Liquid metal sodium boils at 895
0
C. It does not have to be under high pressure as
water does.
…………………………………………………………………………………...……
……………………………………………………………………………....
8.


3.
Though entering the forum of particle physics ………………., he has made himself
……………… well-known with an astonishing assumption about elementary
particles. The forum is always open ………….. for such a figure.

169
4.
Though not refusing…………….. Newton’s theory that light behaves as particles;
Young draw attention of scientists at his time all to his new theory that light behaves
as a wave.
5.
Electrons are the …………..- moving particles in an atom.
6.
Before going on with the details of the report, he presented the content …………….
with an Overhead Projector, getting his audience all ears to him.
7.
He intended to do his experiment ……………… but his supervisor disagreed because
he insisted that the experiment must be conducted in room temperature.
8.
He ..................... reached the goal when he decided to quit the research only because
of financial deficiency.
9.
While lying ……………. on the floor, he suddenly found out the solution to what he
is wondering.
10.
If the north pole of a magnet is brought ………….. the south pole of another, the
poles will attract each other.
PROBLEM - SOLVING
Writing research report (cont.)
In the previous unit, you did have an overview and a sample of what a research report


1.
2.
3.
4.
5.
A. Introduction
6.
for a(n)
M.Sc.Ph.D
.
in X
at the University of Y.
at Y University.
in the Department of Z.

lectures
seminars in Nuclear Physics

relating to
which are related to
Nuclear/ Fusion/
fission/test/reactions

doing
conducting
carrying

in the first week of
at the beginning of
on 1st October
in October
(month)
October
this term
this year

will
continue

until
for
next September.
(the summer of) 200 -.
two more years.
another two years.

I am attending (some)

I am My
To start with
From x
until y
I was studying theoretical aspects of nuclear
fision/fusion/rest/reactions
now I am doing some practical
experiments.
10The aim of
my

work
studies
research
is
to

see if x
show the role of x in y.
suggest ways in which x might be done.
is possible.
exists.
9
13
The result of my research (so far) is that evidence exists to show…
The
most

shows
proves
suggests

that…
14

I have been helped by my
tutor
supervisor
Mr/Ms/Dr./Prof. X
C. Conclusion
16

written
completed
the first
draft
chapter
the outline

…of my

Now that
When