Download QAT 2014 Exam part A

Centre Number
Student Number
2014 HSC TRIAL EXAMINATION
Physics
General Instructions
Total marks – 75
 Reading time – 5 minutes
Section I
 Working time – 2.25 hours
 Write using black or blue pen
 Draw diagrams using pencil
 Board-approved calculators may be used
 Use the multiple-choice answer sheet
provided
 Write your Centre Number and Student
Number at the top of this page and
page 13
Pages 3-25
75 marks
This section has two parts, Part A and Part B
Part A – 20 marks
 Attempt Questions 1-20
 Allow about 35 minutes for this part
Part B – 55 marks
 Attempt Questions 21-31
 Allow about 1 hour and 40 minutes for this
part
Disclaimer
Every effort has been made to prepare this Examination in accordance with the Board of Studies documents. No guarantee or warranty is made or implied that
the Examination paper mirrors in every respect the actual HSC Examination question paper in this course. This paper does not constitute ‘advice’ nor can it be
construed as an authoritative interpretation of Board of Studies intentions. No liability for any reliance use or purpose related to this paper is taken. Advice on
HSC examination issues is only to be obtained from the NSW Board of Studies. The publisher does not accept any responsibility for accuracy of papers which
have been modified.
PHYTR14A_EXAM
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PHYTR14A_EXAM
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2014 HSC TRIAL EXAMINATION
PHYSICS
Part A – 20 marks
Attempt Questions 1-20
Allow about 35 minutes for this part
Use the multiple-choice answer sheet provided for Questions 1-20
Select the alternative A, B, C or D that best answers the question. Fill in the response oval
completely.
Sample
2 + 4 = (A) 2
(B) 6
(C) 8
(D) 9
A
B
C
D
If you think you have made a mistake, put a cross through the incorrect answer and fill in the
new answer.
A
B
C
D
If you have changed your mind and have crossed out what you consider to be the correct
answer, then indicate this by writing the word correct and drawing an arrow as follows:
correct
A
1
B
C
D
The gravitational acceleration on the Earth’s surface is approximately
9.8 m s-2. In order for any planet to have a gravitational acceleration
greater than that of Earth, which of the following properties would it
be necessary for that planet to have?
(A)
A mass greater than that of the Earth
(B)
A radius larger than that of the Earth
(C)
Both larger mass and greater radius than those of the Earth
(D)
None of the above properties is necessarily true for such a planet.
PHYTR14A_EXAM
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The mass of the Moon is 7.4  1022 kg. Its radius is 1 737 km.
Which of the following is nearest to the escape velocity of an object
launched from the Moon’s surface?
2
(A)
vesc = 1 700 m s-1
(B)
vesc = 2 400 m s-1
(C)
vesc = 53 km s-1
(D)
vesc = 75 km s-1.
3
Superconductor
in liquid nitrogen
.
Courtesy of Tom Gordon, Outreach Officer, School of Physics,
Sydney University and the “Kickstart” team of demonstrators.
r = 0.25 m
Track made of a ring of powerful magnets
The Kickstart team at Sydney University has set up a novel example of the phenomenon
of levitation. In this case a circular track of strong magnets allows a superconductor in a
liquid air bath inside a polystyrene box not just to float, but (ignoring air resistance) also
to undergo uniform circular motion when pushed.
In one example the superconductor is found to complete 3 revolutions in 8.0 seconds.
The combined mass of the superconductor, the container and the liquid air is 0.16 kg.
For this example, determine which of the following gives the most correct values of the
orbital speed of the object, and the centripetal force acting on it.
Orbital speed
-1
Centripetal force
(A)
0.59 m s
0.22 N
(B)
0.59 m s-1
11 N
(C)
4.2 m s-1
0.7 N
(D)
4.2 m s-1
11 N
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4
y
x
Consider the graph. The quantities represented by x and y are not provided.
For which of the following formulae could this graph be suitable, if the axes x and y
are renamed as indicated?
x
y
Formula
(A)
EK
v
EK = ½ m v2
(B)
r
T
(C)
Lv
v
(D)
mv
r3
Gm

2
T
4 2
Lv  L0 1  v
mv 
v
2
c2
m0
1  v c 
2
2
Equator
5
The Earth’s radius at the equator is close to 6 380 km,
and its rotational period can be assumed to be exactly
24 hours.
If a new satellite launching station were established at
Woomera in South Australia, which of the following
would best describe the launch velocity advantage,
given its intended orbit?
Woomera
(A)
(B)
464 m s-1
Intended orbit from east → west
more than 464 m s-1 Intended orbit from south → north
(C)
464 m s-1
Intended orbit from west → east
(D)
less than 464 m s-1
Intended orbit from west → east
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6
The Michelson-Morley experiment was a most significant feature in the abandonment
of the theory that light needed a medium, called the aether, to propagate through space
(and other transparent media). Despite the experiment having been carried out many
times in different localities and at different times of the day and year, it almost always
produced a null result, although it was accurate, reliable and valid for its hypothesis.
Which of the following alternatives best describes what is meant by a null result?
(A)
The dependent variable does not change when the independent variable changes
(B)
The dependent variable changes in a non-linear way relative to the independent
variable
(C)
The dependent variable changes in a non-consistent way as the independent
variable is changed
(D)
The dependent variable changes in a way contrary to what the experiment had
predicted as the independent variable is changed.
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The Moon
Alien craft – not to scale
The diagram shows an alien galactic voyager craft approaching the Moon at relativistic
speed. Wary Earthlings are watching the visitors via Multi-vistaTM long-range neutrinobeam scans, and as expected, the chronometers on board the craft verify that their time
is running far more slowly than ours, so the trip from Charon, moon of the dwarfplanet Pluto, has taken minutes with respect to their frame of reference, instead of the
hours as viewed from Earth’s reference frame. If they ever thought about anything,
these aliens would explain the short time required for the trip as being because the
Moon rushed at equally high speed to meet their ship. But that would be incorrect!
Certainly, time on the Moon would certainly appear to be slower from the aliens’ frame
of reference, but even if it travelled at light speed it must still take about 18 hours to
arrive!
How could the aliens actually explain why the trip took less time?
(A)
The distance between Charon and the Moon contracts at relativistic speeds
(B)
The aliens’ frame of reference must be accelerating, and therefore is not inertial
(C)
This is the same as the Twin Paradox where the actual travellers’ view is wrong
(D)
According to relativity, the mass of the craft increases greatly, and this affects
the space-time constant.
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8
The diagram shows a short metal solenoid through which an electric
current is flowing in the direction shown.
Consequently a magnetic field is established around the coil.
I
I
Which of the following 2-dimensional diagrams best displays this
magnetic field?
(A)
(B)
I
9.
(C)
I
I
I
(D)
I
I
I
I
All of the following features is an important part of a functioning DC electric motor,
apart from one.
Which is the incorrect feature?
(A)
Slip-rings to allow current to enter
(B)
A coil free to rotate that turns the armature
(C)
A fairly strong magnetic field to create the motor effect
(D)
An external source of potential difference to provide the current and energy.
10
I
S
The south pole of a bar magnet is brought close to the
western side of a wire carrying DC current due north, as
shown.
What is the direction of the force on the wire?
(A) Due east
(B)
Vertically upwards (out of the page)
(C)
Vertically downwards (into the page)
(D) When the field and current are aligned this way there is no force on the wire.
PHYTR14A_EXAM
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For questions 11 and 12 consider the diagram below.
11
Terminals
The primary coil of this transformer has 100 loops and the secondary coil 400 loops.
When the switch is closed DC electric current passes through the primary coil as
shown.
Which pole is instantly created by the currents on the right-hand end of both the
primary and the secondary coils as we see them?
(A)
A south pole on the right of both the primary and the secondary coils
(B)
A north pole on the right of both the primary and the secondary coils
(C)
A north pole on the right of the primary, and a south pole on the secondary coil
(D)
A south pole on the right of the primary, and a north pole on the secondary coil.
PHYTR14A_EXAM
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Consider once again the transformer shown in the diagram of
Question 11. A cathode-ray oscilloscope is attached across its
terminals, with its time-base set on 0.1 seconds per division.
The switch is closed when t = 0.2 s, and opened when t = 0.7 s.
Which of the graphs best indicates the response detected by the
CRO?
12
(A)
(B)
(C)
(D)
13
A very strong permanent magnet is attached to a string, forming
a simple pendulum when suspended from a clamp attached to a
retort stand.
The magnet is then pulled back, and allowed to swing between
the sides of a U-shaped channel made of aluminium.
The pendulum comes to a stop very quickly. What is the main
reason it stops so abruptly?
(A)
(B)
(C)
The magnet is attracted by the metal of the channel, and sticks to it
The changing field induces an emf that opposes the magnet’s motion
The magnet is repelled by the metal of the channel, spins, and hits its sides
(D)
The magnet’s poles attract or repel electrons as they move across the metal.
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L
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An aircraft is flying due south at cruising speed above a point
where Earth’s magnetic field is directed vertically downwards.
An emf is induced between the tips of the plane’s wings.
To which of the wingtips, L or R, do electrons move, and
which wingtip becomes positively charged?
(A)
Electrons move towards wingtip R, so it becomes positively charged
(B)
Electrons move towards wingtip L, so it becomes positively charged
(C)
Electrons move towards wingtip R, so wingtip L becomes positively charged
(D)
Electrons move towards wingtip L, so wingtip R becomes positively charged.
15
This diagram shows the interference pattern caused when a stream
of X-rays are scattered from the surface of sodium chloride.
Which of the following physicists would have found patterns such
as this significant in the experiments they were carrying out?
(A)
Bardeen, Cooper and Schrieffer in experiments to explain superconductivity
(B)
Wilhelm Hertz in his experiments to find the velocity of electromagnetic rays
(C)
William and Lawrence Bragg in their experiments to determine crystal shapes
(D)
Thomson in his experiments with cathode-rays to find the q/m ratio of electrons
PHYTR14A_EXAM
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16
V
...
Many experiments involving cathode-rays were carried out in the later part of the 19th
century by Julius Plucker, William Crookes and others, the aim being to discover their
properties in order to determine their nature. Some of these experiments led to the
following results:
(I) The tube with a fluorescent plate demonstrated that cathode-rays are deflected by
a magnetic field.
(II) The Maltese Cross tube established that cathode-rays move in straight lines, and
form “shadows” behind barriers.
(III) The Geissler tube confirmed that cathode-rays cause fluorescence on the glass
behind the anode.
(IV) The paddle-wheel tube showed that cathode-rays possess momentum and kinetic
energy.
(V) A cathode-ray tube with photographic film in darkness verified that cathode-rays
expose photographic film.
Which of the following identifies the properties of cathode-rays that exclusively give
support to the British view of the nature of this radiation?
(A)
(I) and (IV) only
(B)
(III) and (V) only
(C)
(I), (II) and (IV) only
(D)
(II), (III) and (V) only.
PHYTR14A_EXAM
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17
6.00 μm
This diagram represents a photon of electromagnetic radiation
that strikes a metal having a work function  = 3.85  10-19 J.
Which of the following identifies the frequency of the photon,
the energy it possesses, and whether it releases a photoelectron?
Frequency [Hz]
Photon energy [J]
Releases photoelectron?
(A)
5.0  1013
3.3  10-20
yes
(B)
5.0  1013
3.3  10-20
no
(C)
6.0  1014
4.0  10-19
no
(D)
6.0  1014
4.0  10-19
yes
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A Coolidge X-ray tube; source Wikipedia
Why was it initially so difficult to observe the interference or diffraction of X-rays?
(A)
They are invisible to the naked eye
(B)
At first it was not known what materials would cause them to diffract
(C)
At that time there was no photographic film that would respond to X-rays
(D)
Their wavelengths are extremely short, so effective gratings could not be made.
PHYTR14A_EXAM
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19
Examine the diagrams below, representing band theory diagrams of various materials:
(I)
(III)
(II)
(IV)
One diagram represents undoped silicon, one is silicon doped with a valence-5
impurity, one is silicon doped with a valence-3 dopant, and one is undoped sulfur.
Which of the alternatives below identifies each of these in their correct order?
20
(A)
(II), (I), (IV), (III)
(B)
(III), (I), (IV), (II)
(C)
(II), (IV), (I), (III)
(D)
(III), (IV), (I), (II).
Consider the graph below, which indicates the relationship between the electrical
resistance of a certain substance as its temperature is reduced towards Absolute Zero.
Resistance (mΩ)
20
15
10
5
0
20
10
30
40
50
Temperature (K)
Which of the following statements is certainly true about the material being tested?
(A)
It is not a superconductor
(B)
It is a type-1 metal superconductor
(C)
It is a type-2 alloy or metal-metal compound superconductor
(D)
It is a high-temperature superconductor made of a complex ceramic.
PHYTR14A_EXAM
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Centre Number
Student Number
Part B – 55 marks
Attempt Questions 21-31
Allow about 1 hour and 40 minutes for this part
Answer the questions in the spaces provided.
Show all relevant working in questions involving calculations.
Question 21 (5 marks)
Marks
A 12-kg rock is initially located at a distance 40 000 km
from the centre of Earth, which has a mass of 6.0  1024
kg. The rock it is stationary in its own reference frame.
Rock – not
to scale
(a)
Determine the gravitational potential energy of the rock at its given location.
(b) Assess whether the rock’s frame of reference could be considered inertial.
1
2
PHYTR14A_EXAM
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(c)
Subsequently the rock will become a meteorite when the Earth’s atmosphere hits
it due to its orbit around the Sun. The rock will heat up and become a “fireball”.
Describe how this can occur since in its reference frame it had no kinetic energy.
Marks
2
Question 22 (5 marks)
16 m s-1
16 m s-1
Parachute
60
Parachute
60
Robert made a device that launches a projectile at 16 m s-1 at an angle 60 above the
horizontal, as shown in the diagram. The projectile is a sphere wrapped in a parachute.
Exactly 1.5 s after being launched the parachute opens instantly, causing the sphere to
fall vertically down at a constant velocity until it reaches the ground. Its speed as it
falls is identical to its vertical velocity when the parachute opened.
(a) What is its vertical displacement when the parachute opens?
2
(b) How long after the parachute opens does it take the projectile to drop back to the
same level from which it was launched?
2
(c) What is its horizontal displacement when it drops back to that same point?
1
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Question 23 (4 marks)
Sputnik-1 Replica; from Wikipedia
Marks
In the late afternoon of 4th October 1957 Australians
looking overhead could observe for the first time a small
bright dot visibly moving across the sky. It was Sputnik-1,
the first artificial satellite launched into orbit. [In fact it
was really the rocket that was used to launch the satellite
into orbit, which having exhausted its fuel was now in
orbit itself.]
Just 96 minutes later, although the Sun had disappeared
below the horizon and the sky was black, the moving craft
could again be observed moving in its orbit as it was high
enough to still be able to catch and reflect sunlight.
(a) Given that the mass of the Earth is 6.0  1024 kg, determine the radius of orbit of
Earth’s first artificial satellite (assuming it to be circular, although it was not).
3
(b) Use the above information to calculate the orbital speed of Sputnik-1.
1
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Question 24 (4 marks)
Marks
In 1905 Albert Einstein proposed his revolutionary
theory of special relativity, by introducing two key
postulates.
Einstein in a library, from Biography.com
(a) Write down Einstein’s two postulates.
2
(b) Describe one consequence of either of Einstein’s postulates
1
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(c) Write down the modern definition of the metre, based on special relativity.
1
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Question 25 (8 marks)
Marks
Direction of current
Students have been asked to test Ampere’s Law. They place a 40-cm length of stiff
copper wire on the top of an accurate electronic balance and connect it to the output of
a potentiometer so they can vary the DC current flowing through it. The current is
directed due north. A horizontal uniform magnetic field is set up between two lines of
powerful rare earth magnets on either side of the wire.
The readings the students obtain as the current is varied are shown in the table below.
Notice that the readings on the electronic balance are in kilograms:
Current (A)
Reading (kg)
.
(a)
(b)
0.25
0.0039
0.75
0.0071
1.00
0.0090
1.50
0.0120
2.00
0.0153
Use the axes provided below to design an appropriate graph of the relationship
between the current through the wire and the readings on the balance, including
the consequent line of best fit.
4
Use the graph to determine the mass of the 40-cm length of wire
1
PHYTR14A_EXAM
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(c)
Marks
From the graph find the magnitude and direction of the external magnetic field.
3
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Question 26 (6 marks)
Marks
Consider the following data concerning the (pure) metals aluminium and copper:
Metal
Aluminium
Copper
Resistivity (20C)
2.65  108 Ω m
1.68  108 Ω m
Density
2.70 kg m-3
8.92 kg m-3
Stress  strain
70 GPa
130 GPa
Points to consider:
* the higher a metal’s resistivity the larger the resistance of otherwise identical cable;
* the greater its density the heavier an identical length of cable will be to work with;
* the higher the stress : strain ratio the more the cable sags when strung between
pylons.
Discuss why copper wire is commonly used for domestic, commercial and industrial
electric circuitry, whereas aluminium is used for cross-country power cables.
6
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Question 27 (4 marks)
Marks
A certain laptop computer requires an input of 19.6 volts DC, which is provided by its
power adaptor. In Australia the input to these is normally the 240 V AC supply.
(a) Using a labelled diagram outline the principle of mutual induction for
transformers.
2
(b) What is the ratio of the number loops on the primary coil of the adaptor for this
laptop to the number of loops on its secondary coil?
1
(c) Briefly describe how the input AC is converted into the necessary DC output for
today’s modern laptop computers.
1
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Question 28 (5 marks)
The HSC syllabus requires students to process information to discuss Einstein and
Planck’s differing views about whether science research is removed from social and
political forces.
Marks
5
Consider the following excerpt from an article by reporter Andrew Trounson in the
Features Section of ‘The Australian’ newspaper of 11th September 2013, headed,
“Culture of secrecy `stifles research value”:
“University research culture is too closed, inward looking and out of step with a global
trend towards openness and collaboration,’ Microsoft Australia’s chief technology
officer Greg Stone says. He claims the incentive system is out of kilter with the growing
need for research to be ‘liberated’ into broader society. Instead, academics are
encouraged to build their careers by jealously guarding their research instead of
applying the fruits of their discoveries.”
Assess the article that quotes the opinion about current research expressed by Mr Stone,
in relation to the differing opinions of Einstein and Planck 100 years ago, citing wellknown examples to support your opinion.
PHYTR14A_EXAM
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Question 29 (6 marks)
Marks
+30 V
2.4 cm
electron
4.5 cm
0V
The upper of a pair of parallel aluminium plates 2.4 cm apart carries a potential of
+30 V. The lower plate is earthed, so its potential is zero. An electron moving due
west at 5.4  106 m s-1 is about to pass between them.
The two plates are 4.5 cm long, as shown in the diagram.
(a)
+30 V
1
0V
Use eight (8) directed lines to sketch the electric field set up between the
plates.
(b)
Determine the force acting on the electron as it passes through this field.
2
(c)
Find the magnitude of the impulse of the force acting on the electron during
the time it is passing across the electric field.
1
(d)
Determine the magnitude and direction of a magnetic field required to allow
the electron to pass through between the plates without deviation.
2
PHYTR14A_EXAM
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Question 30 (4 marks)
Marks
The above graph, representing the relationship between two variables, caused much
controversy towards the end of the 19th century, because the theoretical relationship
did not match this, the experimental one.
(a)
What does this graph represent?
1
(b)
Identify appropriate labels for the axes of the graph:
1
x-axis
(c)
y-axis
Describe why this graph was so controversial near the end of the 19th century.
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2
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Question 31 (4 marks)
Marks
(a) Which was the first semiconductor in common use?
1
(b) Outline reasons why it was replaced by silicon.
2
(c) Describe how (electron) holes “migrate” through a crystal.
1
PHYTR14A_EXAM
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