NAME Solutions
MEDIA ANALYSIS QUESTIONS (21 Marks)
1
Give a summary of the article in approximately 200 words.
Atoms are not just made of protons, neutrons and electrons but there exists a huge array of sub-sub atomic
particles which are now included in the Standard Model for all matter, eg leptons, quarks and gauge bosons
and all of these have anti-matter equivalents. The most recently discovered Higgs boson explains how matter
acquired mass.
Quarks are the most interesting because they help us understand what protons and neutrons are made of.
There are six types of quarks: up, down, top, bottom, charm and strange. Nobody knows why there are so
many when only two types, up and down quarks, are needed to make up protons and neutrons.
Surprisingly, quarks are not 1/3 of the mass of a proton or a neutron – but much lighter. However, some quarks
are very heavy – eg the top quark is heavier than most atoms. They are also much smaller in size than
expected; of the order of 10-20m compared with 10-15m for the proton. Lending support to the theory that
atoms are mostly made of empty space.
Preon is the name given to the possible sub-sub-sub-atomic particles that may exist. It is also possible that
even smaller particles exist in the form of tiny strings.
5 marks
2
Before our knowledge of quarks was developed, what were the three basic building
blocks of the atom assumed to be?
Protons, neutrons and electrons
3 marks
3
Give the names of the 6 varieties of quarks.
Up, down, top, bottom, strange and charm
3 marks
4
Explain what is surprising about the mass of quarks? (Mention at least 3 quarks
in your response).
They are much much lighter than expected –
eg up and down quarks account for only 2% of the mass of the proton or neutron they combine to
form.
The top quark is much heavier than most atoms and roughly compares to the mass of tungsten.
3 marks
5 How much time elapsed between the discoveries of the 5th and 6th quarks?
18 years, the bottom quark was discovered in 1977 and the top quark in 1995.
1 mark
6
What explanation is given for the difference between expected and actual mass of
the quarks which combine to form hadrons?
Quarks are like Styrofoam flecks blowing in a wind.
The wind represents the strong nuclear force which holds them together, which accounts for
the 98% of the mass they acquire when combined to form protons or neutrons.
That mass is the Einsteinian mass equivalent of the energy represented by that force.
3 marks
7
Fill in the table below regarding the relative size, of each particle and sub-particle
from smallest to largest?
Particle or sub-particle
Order of Magnitude – include units
Quarks
10-20 m
Protons
10-15 m
Atoms
10-10 m
3 marks