Student Number

2013
TRIAL HSC Mark / 100
EXAMINATION

Physics

General Instructions Total Marks – 100

Section I Pages 2 - 22
• Reading time – 5 minutes
• Working time – 3 hours 75 marks

Confidential
• Write using black or blue pen
• Draw diagrams using pencil This section has two parts, Part A and Part B

Keep Secure
• Write your Student Number at the top of this page
Part A – 20 marks
and on the response sheets on page 10 and 11
•Attempt Questions 1- 20
• Board-approved calculators may be used •Allow about 30 minutes for this part
• A data sheet and a Periodic Table are provided
Part B – 55 marks
•Attempt Questions 21 - 31
•Allow about 1 hour and 45 minutes for this part

Section II Page 23

25 marks

•Attempt Question 32
•Allow about 45 minutes for this section

JRAHS 2013 Physics HSC Trial Examination Page 1

Section I
75 marks

Part A – 20 marks
Attempt Questions 1-20
Allow about 30 minutes for this part

Use the multiple choice answer sheet on page 10.

JRAHS 2013 Physics HSC Trial Examination Page 2

1. A person stands on a scale in an elevator. He notices that the scale reading is lower than his
normal ‘weight’.

Which of the following could possibly describe the motion of the elevator?

(A) It is moving up and slowing down.

(B) It is moving up and speeding up.
(C) It is moving down at constant speed.
(D) It is moving down and slowing down.

2. A ball is projected horizontally with a speed of 40 ms-1 from the top of a cliff on the surface of
the Earth.

What will be its approximate speed 3.0 s later if there were no air resistance?

(A) 30 ms-1
(B) 40 ms-1
(C) 50 ms-1
(D) 60 ms-1

3. A moon of a planet Rusean has an orbital period of 5 days and is at a distance of 5 units from the
centre of the planet. Another moon is discovered at a distance of 20 units from the centre of Rusean.

Which of the following will be closest to the orbital period of the newly discovered moon?

(A) 40 days
(B) 20 days
(C) 13 days
(D) 5 days

4. The Space Shuttle orbits 300 km above the Earth's surface. If the Earth's radius is 6400 km, what
is the gravitational acceleration experienced by the Space Shuttle while in this orbit?

(A) 4.9 ms-2

(B) 8.9 ms-2
(C) 9.8 ms-2
(D) 10.8 ms-2

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5. The minimum initial velocity required by a space probe to just escape the gravitational pull of a
planet is called escape velocity.

Which of the following quantities does NOT affect the magnitude of the escape velocity?

(A) mass of the planet

(B) mass of the space probe
(C) radius of the planet
(D) universal gravitational constant

6. The gravitational potential energy of two masses at a distance 2.0 m apart is - 8.0 J.

What external work must be done on this system to separate the masses to a distance of 4.0 m?

(A) - 4.0 J
(B) - 2.0 J
(C) + 2.0 J
(D) + 4.0 J

7. Astronauts on a long space journey are playing golf inside their spaceship, which is travelling away
from the Earth with speed 0.6 c . One of the astronauts hits a drive exactly along the length of the
spaceship (in its direction of travel) at speed 0.1 c in the frame of the spaceship.

What is the speed of the golf ball as observed from Earth?

(A) 0. 74 c
(B) 0.7 c
(C) 0.66 c
(D) 0.5 c

8. How does a moving coil galvanometer operate?

(A) by balancing the torque on a current-carrying coil with the torque on a coil spring

(B) by balancing the current induced in a coil with the applied current

(C ) by producing a magnetic field that is balanced by a coil spring

(D) by inducing a current in the coil that is placed in a magnetic field

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9. A current flows in a straight wire placed perpendicular to a uniform magnetic field. The current
varies with time as shown on the diagram below.

Which statement best describes the magnetic force acting on the wire?

(A) It has a constant magnitude but changing direction.

(B) It has both a constant magnitude and direction.
(C) It has both a changing magnitude and direction.
(D) It has a changing magnitude but constant direction.

10. The figure below shows a straight wire carrying a steady current from X to Y. The wire is
suspended between the poles of two similar permanent magnets, each of which produces a
uniform magnetic field between the N and S poles.

What will the wire experience?

(A) a force in the direction XY

(B) a force in the upward direction
(C) a torque tending to rotate the wire about an axis parallel to the magnetic field
(D) no resultant force

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11. A copper ring hangs vertically from a thread with its axis along the axis of a coil as shown in the
diagram.

What is the initial direction of motion of the copper ring when the switch K is closed?

(A) P

(B) Q

(C) R

(D) S

12. A straight current-carrying conductor is placed within an external magnetic field as

shown below.

What is the magnitude of the force on the conductor carrying a current of 3 A?

(A) 0.12 N
(B) 0.15 N
(C) 0.18 N
(D) 0.24 N

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13. A simple DC motor has n turns of wire in the armature and has an area of A m2. A current of I
o
amperes passes through the armature. The plane of the armature is at 0 to the direction of the
magnetic field of strength B Teslas.

What is the torque on the armature if the area and the current are doubled and the armature is at
o
an angle of 60 to the magnetic field direction?

(A) twice the original torque

(B) four times the original torque
(C) equal to the original torque
(D) half the original torque

14. AC induction motors are commonly used in small power tools around the home.
Which of the following statements correctly describes the working of an AC induction motor?

(A) A changing magnetic flux from the stator induces a current in the rotor causing it to spin in the
same direction as the changing field.

(B) A constant magnetic flux from the stator induces a current in the rotor causing it to spin in the
same direction as the field.

(C) A changing magnetic flux from the stator induces a current in the rotor causing it to spin in the
opposite direction to the changing field.

(D) A constant magnetic flux from the stator induces a current in the rotor causing it to spin in the
opposite direction as the field.

15. At room temperature, what is the current in an intrinsic semiconductor due to?

(A) movement of holes

(B) movement of electrons
(C) movement of holes and electrons
(D) none of the above

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16. Which of the following correctly describes a photon?

(A) It is a unit of energy,

(B) It is an electron emitted from a metal surface by the action of light.
(C) It is an electron emitted from a metal surface by the action of heat.
(D) It is a quantum of electromagnetic radiation.

17. William Bragg and his son Lawrence studied crystals and Lawrence determined the mathematical
formula:
n λ = d sin 

Which of the following did this formula allow them to determine?

(A) the number of electrons in an atom

(B) the mass of atoms
(C) the charge on an electron
(D) the internal arrangement of atoms in crystals

18. Which statement, according to the BCS theory of superconductivity, is correct?

(A) Superconductivity occurs because the crystal lattice causes electron pairs to break up.
(B) Distortions of the crystal lattice by electron movement cause superconductivity to cease.
(C) Distortions of the crystal lattice allow electrons to pair up and flow unimpeded.
(D) Superconductivity occurs because low temperatures cause the crystal lattice to stop vibrating
and remain free from distortion.

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19. The following is a list of some possible properties of high temperature superconductors. Some may be
incorrect.

1. Relatively hard to produce

2. Only made from metals
3. Not very ductile
4. Can be brittle

Which of the above would be considered as correct limitations to modern high temperature
superconductors?

(A) 2 and 3
(B) 1, 3 and 4
(C) 2, 3 and 4
(D) 1, 2, 3 and 4

20. Inside a discharge tube producing cathode rays, a freely rotatable wheel is mounted. When cathode
rays fall on it the wheel starts rotating.

What does this experiment indicate about cathode rays?

(A) Cathode rays are charged particles.

(B) Cathode rays are energetic rays.
(C) Cathode rays are particles having momentum.
(D) Cathode rays are electromagnetic waves.

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 Student Number ……………………

Section I Mark ----- /20

Part A

Multiple Choice Answer Sheet

1. A B C D

2. A B C D

3. A B C D

4. A B C D

5. A B C D

6. A B C D

7. A B C D

8. A B C D

9. A B C D

10. A B C D

11. A B C D

12. A B C D

13 A B C D

14. A B C D

15. A B C D

16. A B C D

17. A B C D

18. A B C D

19. A B C D

20. A B C D

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 Part B 55 marks Student No. …………………
Attempt questions 21 - 31
Allow about 1 hour and 45 minutes for this part
Show all relevant working in questions involving calculations

Question 21 (6 Marks) Marks

An archer shoots an arrow at a 22o angle to the horizontal. At the top of its motion, the arrow
just clears a 36 m high gum tree.

(a) Determine the speed of the arrow when it left the bow. 3
Assume it was shot from 1 m above the ground.

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(b) How far away is the archer from the foot of the tree? 3

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 Question 22 (5 marks) Marks

The following information applies to the Space Shuttle during the first 120 seconds of its launch.

Mass of space shuttle at 0 s 2 051 113 kg

Thrust force from the rocket engines is constant by first-stage burn 3.0 x 107 N
Mass loss per second due to rocket discharge of fuel 1.3 x 104 kg
Frictional forces due to the atmosphere decrease with height

(a) Describe qualitatively and quantitatively how the g forces acting on the astronauts vary 4
during the first 120 seconds.
Compare them to the g forces on the astronaut while the rocket is at rest.

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(b) Sketch two graphs, on the same axes, to show how the velocity and kinetic energy of the 1
shuttle varies during the first 120 seconds. (No numerical values are required).
Use different labelled lines to show velocity and kinetic energy.
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0 120 t (s)

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 Question 23 (5 marks) Marks

Assess the use of thought experiments in the development of our current understanding of time.

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 Question 24 (7 marks) Marks

A closed loop is made of a U-shaped metal wire of negligible resistance and a movable metal
crossbar of resistance R. The crossbar has mass m and length L. It is initially located a distance
h0 from the other end of the loop. The loop is placed vertically in a uniform horizontal magnetic
field of magnitude B0 in the direction shown in the figure above.

Express all algebraic answers to the questions below in terms of B0, L, m, h0, R, and fundamental
constants, as appropriate.

(a) Determine the magnitude of the magnetic flux through the loop when the crossbar is in the 1
position shown.

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The crossbar is released from rest and slides with negligible friction down the U-shaped wire
without losing electrical contact.

(b) On the figure below, indicate the direction of the current in the crossbar as it falls. 3
Justify your answer.

crossbar

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Question 24 continues on the next page

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 Question 24 (continued) Marks

(c) If the resistance, R, of the crossbar now is increased, will the initial speed of the crossbar 1
increase, decrease, or remain the same as before?

Circle the correct answer below.

Increases Decreases Remains the same

\

(d) Justify your answer in (c) in terms of the forces on the crossbar. 2

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 Question 25 (4 marks) Marks

A student conducts two investigations with a bar magnet. First, a bar magnet is suspended
horizontally by a piece of thread and allowed to oscillate about a vertical axis through its centre,
(i) above a piece of glass plate, and then
(ii) above a piece of copper plate.

Describe and explain what the student will observe in each investigation.

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 Question 26 (2 marks) Marks

Models are often used in Science to explain phenomena. The model below is found in a
textbook and is used to explain conduction in semi-conductors, conductors and insulators.

The model correctly explains semi-conductors and insulator behaviour.

In conductors, with reference to the diagram, what aspect of metal conductivity behaviour does
the model not explain?

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 Question 27 (4 marks) Marks

(a) An ideal transformer has a primary coil with 36 loops, a current of 0.900 A and a voltage 1
of 7.0 V.

What is the voltage of the secondary coil if it’s current is 0.675 A?

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(b) With the same primary coil described in (a), how many loops will need to be in the secondary 1
coil to have a current of 2.7 A?

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(c) Why are transformers dependent on AC current? 2

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 Question 28 (5 Marks) Marks

Assess the impact on society and the environment of the potential applications of superconductors
in motors and generators, and in power transmission.

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 Question 29 (4 marks) Marks

(a) With the aid of a labelled diagram, explain briefly how electrons are produced in a 2
Cathode Ray Oscilloscope.

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(b) Outline how these electrons are given a high velocity. 1

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(c) Outline how the beam of electrons can be made to move vertically. 1

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 Question 30 (8 Marks) Marks

In a photoelectric emission experiment, a metal surface in an evacuated tube is illuminated

with monochromatic light and a current is detected. If the experiment is repeated with light of
the same wavelength but of twice the intensity, explain how it would affect the following:
(a) the energy of the photon,
(b) the maximum kinetic energy of the photoelectrons,
(c) the work function of the metal,
(d) the photoelectric current.

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 Question 31 (5 marks) Marks

A student performed an experiment to determine the strength of a constant, uniform magnetic

field by measuring the radius of the path of a beam of electrons moving at various speeds in a
this magnetic field.

The student’s data is presented below.

v ( 107 ms-1) r ( 10-3 m)

1.0 0.6
2.0 1.1
3.0 1.7
4.0 2.3
5.0 2.8

(a) Plot the data from the table and draw a graph. 1

radius
r 3
( 10-3 m)

0
0 1 2 3 4 5
speed v ( 107 ms-1)

Question 31 continues on the next page

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 Question 31 (continued) Marks

(b) Use the gradient of the graph to determine the magnitude of the magnetic field as electrons 4
move in their circular paths. Show all working.

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 Section II

Question 32– From Quanta to Quarks (25 marks) Marks

Allow about 45 minutes for this section

(a) When hot hydrogen vapour is viewed through a spectrometer, four distinct bright lines of
the Balmer series can be seen. The wavelengths of these lines are given in the table below.

Balmer series
6.562 x 10-7 m
4.861 x 10-7 m
4.340 x 10-7 m
4.102 x 10-7 m

(i) By referring to the Bohr model of the atom, describe how these lines are formed. 2

(ii) Apply the Rydberg equation to show how any ONE of the lines can be predicted. 2

(b) (i) The nuclide decays to the nuclide in 4 successive radioactive decays. 1
Each decay involves the emission of either an alpha or a beta particle.

What is the value of A ?

(ii) The actual mass of the atom is 119.9045 u. Calculate its mass defect, given 1
the following data:

Proton mass 1.0073 u

Neutron mass 1.0087 u
Electron mass 0.00055 u

(iii) What is the energy equivalent of this mass defect? 1

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Question 32 (continued) Marks

(c) (i) Using a labelled diagram outline ONE way in which physicists obtain particles with 5
the appropriate energy to investigate the structure of matter.

(ii) Give ONE other application of the technology outlined above. 1

(d) Describe how de Broglie’s proposal was confirmed by Davisson and Germer. 4

(e) The diagram shows a fission nuclear reactor.

(i) Identify the parts labelled 2 and 3 in the diagram. 2

(ii) State the function of the parts labelled 1 and 3 in the diagram. 2

(f) Until the second half of the twentieth century, the proton, neutron and electron were thought 4
to be fundamental particles of matter.

Justify how the introduction of quarks and leptons, and strong and weak forces in the
standard model, has changed our understanding of particle physics.

End of examination

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