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Measurement, STD2 M6 2022 HSC 33

The diagram shows an aeroplane that was flying towards an airport at  on a bearing of . When it was at point , 20 km away from the airport at  , the flight course was changed. The aeroplane landed at an airport at directly south of . The distance from to is 50 km.
 


 

  1. Show that the distance between the airport at  and the airport at is 38.5 km, correct to 1 decimal place.  (2 marks)

  2. Use the sine rule to find the angle to the nearest degree.  (2 marks)

  3. What is the bearing of the airport at from the airport at  ?  (1 mark)

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Show Worked Solution

a.   
 

 
   
 
   

♦ Mean mark part (a) 50%.

 

b.   

 
 
 
   
   

♦♦ Mean mark part (b) 39%.

 

c. 


♦♦ Mean mark part (c) 25%.

Measurement, STD2 M1 2022 HSC 32

The diagram shows a park consisting of a rectangle and a semicircle. The semicircle has a radius of 100 m. The dimensions of the rectangle are 200 m and 250 m.

A lake occupies a section of the park as shown. The rest of the park is a grassed section. Some measurements from the end of the grassed section to the edge of the lake are also shown.
 

  1. Using two applications of the trapezoidal rule, calculate the approximate area of the grassed section.  (2 marks)

  2. Hence calculate the approximate area of the lake, to the nearest square metre.   (2 marks)

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Show Worked Solution

a.   

 
   
   
   

 

b.   
   
   

 

 
   

♦ Mean mark (b) 44%.

Networks, STD2 N3 2022 HSC 31

A wildlife park has 5 main attractions connected by directional paths. A simple network is drawn to represent the flow through the park's paths. The number of visitors who can access each path at any one time is also shown.
 

   

  1. What is the flow capacity of the cut shown?  (1 mark)

  2. By showing a suitable cut on the diagram below, explain why the network's current maximum flow capacity is less than 40 visitors.  (2 marks)
     

  3. One path is to be increased in capacity so that the overall maximum flow will be 40 visitors at any one time.
  4. Which path could be increased and by how much?  (2 marks)

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  2.  
     
Show Worked Solution

a.   


 

b.  
       

 
   


♦ Mean mark part (a) 45%.
♦♦ Mean mark part (b) 33%.

 

c.   

 


Mean mark 52%.

Financial Maths, STD2 F5 2022 HSC 30

Eli is choosing between two investment options.

A table of future value interest factors for an annuity of $1 is shown.

  1. What is the value of Eli's investment after 10 years using Option 1 ?  (2 marks)

  2. What is the difference between the future values after 10 years using Option 1 and Option 2?  (2 marks)

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a.   

 
   
   

 


♦ Mean mark 48%.

b.   

 
   

 

 
   

♦ Mean mark 43%.

Measurement, STD2 M1 2022 HSC 28

A dam is in the shape of a triangular prism which is 50 m long, as shown.

Both ends of the dam, and , are isosceles triangles with equal sides of length 25 metres. The included angles and are each .

 
     

Calculate the number of litres of water the dam will hold when full.  (4 marks)

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Show Worked Solution

 
   
   

 

 
   

 

³

 
   

♦♦ Mean mark 33%.

Financial Maths, STD2 F4 2022 HSC 27

A company purchases a machine for $50 000. The two methods of depreciation being considered are the declining-balance method and the straight-line method.

  1. For the declining-balance method, the salvage value of the machine after years is given by the formula
  2.    
  3. where is the salvage value and is the initial value of the asset.
  4.  i. What is the annual rate of depreciation used in this formula?  (1 mark)
  5. ii. Calculate the salvage value of the machine after 3 years, based on the given formula.  (1 mark)
  6. For the straight-line method, the value of the machine is depreciated at a rate of 12.2% of the purchase price each year.
  7. When will the value of the machine, using this method, be equal to the salvage value found in part (a) (ii)?  (2 marks)
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  1.  i.
  2. ii.
Show Worked Solution

a.i. 
 

a.ii. 

 
   
   

 
b.   

 
   

 

 
 
 
   

♦♦ Mean mark (a.i.) 24%.
COMMENT: A poor State result in part (a.i.) that warrants attention.
 
♦ Mean mark part (b) 38%.

Measurement, STD2 M6 2022 HSC 26

The diagram shows two right-angled triangles, and ,

where and .
 
     

Calculate the size of angle , to the nearest minute.  (4 marks)

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Show Worked Solution

 
 
   

 

 

 
 
 
   
   

♦ Mean mark 50%.

Financial Maths, STD2 F5 2022 HSC 25

The table shows the future value of an annuity of $1.
 
     

Zal is saving for a trip and estimates he will need $15 000. He opens an account earning 3% per annum, compounded annually.

  1. How much does Zal need to deposit every year if he wishes to have enough money for the trip in 4 years time?  (2 marks)

  2. How much interest will Zal earn on his investment over the 4 years? Give your answer to the nearest dollar.  (2 marks)

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Show Worked Solution

a.   

 
 
 
   

 

b.   

 
   
   
   

♦♦ Mean mark 33%.

ENGINEERING, PPT 2021 HSC 22a

A baseplate used to support the wheels under a trolley is shown in pictorial view.

Construct, within the dashed-line box provided, a top view of the baseplate. Do NOT dimension.   (3 marks)
 

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Top view

Show Worked Solution

Top View


♦ Mean mark 42%.

Statistics, STD2 S1 2022 HSC 19

The table shows the types of customer complaints received by an online business in a month.
 

  1. What are the values of and ?  (2 marks)

  2. The data from the table are shown in the following Pareto chart.
     
     
  3. The manager will address 80% of the complaints.
  4. Which types of complaints will the manager address?  (1 mark)

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Show Worked Solution

a.   


 

b.   


♦ Mean mark part (b) 41%.

Measurement, STD2 M7 2022 HSC 4 MC

Lily wanted to estimate the number of fish in a lake.

She randomly captured 30 fish, then tagged and released them.

One week later she randomly captured 40 fish from the same lake. She found that 12 of these 40 fish were tagged.

What is the best estimate for the total number of fish in the lake?

  1. 58
  2. 70
  3. 82
  4. 100
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Show Worked Solution

 
 
 
   

 


♦♦ Mean mark 37%.

PHYSICS, M7 2019 HSC 25

The diagram shows a model of electromagnetic waves.
 


 

Relate this model to predictions made by Maxwell.   (4 marks)

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→ The diagram shows alternating electric and magnetic fields oscillating perpendicular to each other. This relates to Maxwell’s prediction of mutual inductance; that a changing electric field induces a changing magnetic field and vice versa.

→ The diagram shows the electromagnetic wave propagating with velocity . This relates to Maxwell’s prediction of a range of waves with different wavelengths, all travelling at the same speed where .

→ The diagram also shows an electromagnetic wave emanating from an oscillating charge. This is consistent with Maxwell’s prediction that an oscillating electric charge produces a changing electric field, which in turn produces a changing magnetic field. These fields continue to mutually induce each other, producing an electromagnetic wave.

Show Worked Solution

→ The diagram shows alternating electric and magnetic fields oscillating perpendicular to each other. This relates to Maxwell’s prediction of mutual inductance; that a changing electric field induces a changing magnetic field and vice versa.

→ The diagram shows the electromagnetic wave propagating with velocity . This relates to Maxwell’s prediction of a range of waves with different wavelengths, all travelling at the same speed where .

→ The diagram also shows an electromagnetic wave emanating from an oscillating charge. This is consistent with Maxwell’s prediction that an oscillating electric charge produces a changing electric field, which in turn produces a changing magnetic field. These fields continue to mutually induce each other, producing an electromagnetic wave.


♦ Mean mark 44%.

PHYSICS, M6 2019 HSC 24

A step-up transformer is constructed using a solid iron core. The coils are made using copper wires of different thicknesses as shown.
 

The table shows electrical data for this transformer.
 

  1. Explain how the operation of this transformer remains consistent with the law of conservation of energy. Include a relevant calculation in your answer.   (3 marks)
  1. Explain how TWO modifications to this transformer would improve its efficiency.   (4 marks)
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a.    The energy input into this transformer is 500 J

The energy output is given by:

 
   
  J  

 
This is consistent with the law of conservation of energy as 500 J of energy is converted into other energy forms such as heat.
   

b.    → Laminating the iron core prevents large eddy currents from being induced in it.

→ This reduces energy loss in the form of heat, increasing efficiency.

→ Increasing the thickness of the wire in the primary coil reduces its resistance, increasing the transformer’s efficiency.

Show Worked Solution

a.   The energy input into this transformer is  500  J

The energy output is given by:

 
   
  J  

 
This is consistent with the law of conservation of energy as 500 J of energy is converted into other energy forms such as heat.
   

b.     Modification 1:

→ Laminating the iron core prevents large eddy currents from being induced in it.

→ This reduces energy loss in the form of heat, increasing efficiency.

Modification 2:

→ Increasing the thickness of the wire in the primary coil.

→ This reduces its resistance, increasing the transformer’s efficiency.


♦ Mean mark part 48%.

PHYSICS, M5 2019 HSC 20 MC

In the apparatus shown, a backboard is connected by a rod to a shaft. The shaft is spun by an electric motor causing the backboard to rotate in the horizontal plane around the axis  X X′.

A cube is suspended by a string so that it touches the surface of the backboard.
 

When the angular velocity of the motor is great enough, the string is cut and the position of the cube does not change relative to the backboard.

Which statement correctly describes the forces after the string is cut?

  1. The sum of the forces on the cube is zero.
  2. The horizontal force of the backboard on the cube is equal in magnitude to the horizontal force of the cube on the backboard.
  3. The horizontal force of the backboard on the cube is greater than the horizontal force of the cube on the backboard, resulting in a net centripetal force.
  4. The force of friction between the cube and the backboard is independent of the force of the backboard on the cube because these forces are perpendicular to each other.
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Show Worked Solution

Using Newton’s Third Law:

The backboard and the cube are an action-reaction pair.

The force of the backboard on the cube (centripetal force) is equal in magnitude and opposite in direction to the force of the cube on the backboard.


♦ Mean mark 36%.

PHYSICS, M8 2019 HSC 19 MC

Consider the following nuclear reaction.

Information about W, X and Y is given in the table.

Which of the following is a correct statement about energy in this reaction?

  1. The reaction gives out energy because the mass defect of Y is greater than that of either W or X.
  2. It cannot be deduced whether the reaction releases energy because the properties of Z are not known.
  3. The reaction requires an input of energy because the mass defect of the products is greater than the sum of the mass defects of the reactants.
  4. Energy is released by the reaction because the binding energy of the products is greater than the sum of the binding energies of the reactants.
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Show Worked Solution

Energy required to break W and  X  into their constituent nucleons:

Energy released in the formation of the products is given by the sum of binding energies of  Y  and  Z:

binding energy of  Z
   
As this is greater than the sum of binding energies of the reactants regardless of the binding energy of  Z , there is a net release of energy in the reaction.


♦ Mean mark 31%.

PHYSICS, M6 2019 HSC 17 MC

A straight current-carrying conductor, , is connected to a battery and a variable resistor. is enclosed in an evacuated chamber with a fluorescent screen at one end.
 


 

A cathode ray enters the chamber directly above , initially travelling parallel to . It passes through the chamber and strikes the fluorescent screen causing a bright spot.

Which direction will this spot move towards if the resistance is increased?

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Show Worked Solution

Using the right hand grip rule, the current through creates a magnetic field to the right above it. Using the right hand palm rule, this creates an upwards force on the cathode ray, which is made up of electrons.

Increasing the resistance

→ decreased current through

→ decreased upwards force on the cathode ray

→ bright spot moves downwards towards .


♦ Mean mark 36%.

PHYSICS, M6 2019 HSC 16 MC

The diagram shows the trajectory of a particle with charge and mass when fired horizontally into a vacuum chamber, where it falls under the influence of gravity.
 

The horizontal distance, , travelled by the particle is recorded.

The experiment is repeated with a uniform vertical electric field applied such that the particle travels the same horizontal distance, , but strikes the upper surface of the chamber.
 

What is the magnitude of the electric field?

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→ As the particle travels the same distance in both scenarios the magnitude of the force it experiences is the same.

→ Initially, the only force acting on the particle is its weight,

→ When the electric field is on, the particle experiences an upwards force due to the electric field, and a downwards force due to gravity, 

→ As these forces have the same magnitude:

 
 
 

 


♦ Mean mark 42%.

PHYSICS, M5 2019 HSC 14 MC

A satellite in circular orbit at a distance from the centre of Earth has an orbital velocity .

If the distance was increased to , what would be the satellite's orbital velocity?

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Show Worked Solution

The satellites centripetal force is provided by gravity:

 
 
 
 

 
Hence, doubling the satellites radius changes its velocity by a factor of


♦ Mean mark 42%.

PHYSICS, M8 2019 HSC 12 MC

The table shows two types of quarks and their respective charges.
 

In a particular nuclear transformation, a particle having a quark composition is transformed into a particle having a quark composition .

What is another product of this transformation? 

  1. Electron
  2. Neutron
  3. Positron
  4. Proton
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Show Worked Solution

→ The particle with quark composition is a neutron.

→ It is transformed into a particle with quark composition which is a proton.

→ To conserve charge, an electron must also be a product.


♦ Mean mark 51%.

PHYSICS, M5 2019 HSC 9 MC

Two satellites have the same mass. One (LEO) is in low-Earth orbit and the other (GEO) is in a geostationary orbit.

The total energy of a satellite is half its gravitational potential energy.

Which row of the table correctly identifies the satellite with the greater orbital period and the satellite with the greater total energy?

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Orbital velocity decreases as the orbital radius of a satellite increases.

→ the geostationary satellite has the greater orbital period

Total energy increases as orbital radius increases.

→ the geostationary satellite has the greater total energy


♦ Mean mark 43%.

PHYSICS, M6 2019 HSC 7 MC

A bar magnet is moved away from a stationary coil.

Which diagram correctly shows the direction of the induced current in the coil and the resulting magnetic polarity of the coil?
 

 

 

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The current through the solenoid will produce a force that opposes the magnets motion (Lenz’s law).

So, there will be a north pole on the right hand side of the magnet. The right hand grip rule gives the direction of current. 


♦ Mean mark 47%.

PHYSICS, M6 2020 HSC 32

A rope connects a mass on a horizontal surface to a pulley attached to an electric motor as shown.
 

Explain the factors that limit the speed at which the mass can be pulled along the horizontal surface. Use mathematical models to support your answer.   (7 marks)

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The factors limiting the speed of the mass along horizontal surface can be divided into two main parts: Factors involving friction between the mass and the table and factors involving the force output of the motor and pulley.

Friction between the mass and table:

→ The mass will experience a friction force of  . Since the mass has no vertical acceleration, 

→ So, the speed at which the mass can be pulled is limited by the coefficient of kinetic friction between the mass and the table and the magnitude of the mass .

 
Force produced by the motor:

→ The torque produced by the motor is given by 

→ The torque of the motor and hence maximum speed at which the mass can be pulled is limited by the number of turns of the coil in the motor, the current passing through the coils , the area of the coils and the magnetic field strength of the stator magnets .

→  Via the pulley, the torque generated by the motor generates a force which pulls the mass. As , a smaller pulley radius means that a larger force can be used to pull the mass.

→ So, the speed at which the mass can be pulled is limited by pulley radius.

 
Answers could also contain:

→ Back emf in the motor limiting its maximum speed.

→ The efficiency of the motor.

Show Worked Solution

The factors limiting the speed of the mass along horizontal surface can be divided into two main parts; 1-Factors involving friction between the mass and the table and 2-Factors involving the force output of the motor and pulley.

Friction between the mass and table

→ The mass will experience a friction force of  . Since the mass has no vertical acceleration, 

→ the speed at which the mass can be pulled is limited by the coefficient of kinetic friction between the mass and the table and the magnitude of the mass .

 
Force output of the motor and pulley

→ The power of the motor depends on its torque and the pulley radius

→ The torque produced by the motor is given by 

→ The force of the motor and hence maximum speed at which the mass can be pulled is also limited by the number of turns of the coil in the motor, the current passing through the coils, the area of the coils and the magnetic field strength of the stator magnets.

 

Answers could also contain:

→ Back emf in the motor limiting its maximum speed.

→ The efficiency of the motor.

Mean mark 58%.

PHYSICS, M5 2020 HSC 31

  1. The orbit of a comet is shown.

  1. Account for the changes in velocity of the comet as it completes one orbit from position .   (3 marks)
  1. Two stars, and , of equal mass , separated by a distance , interact gravitationally such that the speed of is constant.
  2. Derive an expression for the speed of .   (3 marks)
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a.    Changes in Velocity

→ As the comet moves from position towards the sun, its gravitational potential energy (GPE) is converted into kinetic energy.

→ Increase in the comet’s kinetic energy → increase in the comet’s velocity as it moves towards the sun.

→ As the comet moves away from the sun back to, its kinetic energy is converted into GPE.

→ Decrease in kinetic energy → decrease in comet’s velocity.
 

b.   

Show Worked Solution

a.    Changes in Velocity 

→ As the comet moves from position towards the sun, its gravitational potential energy (GPE) is converted into kinetic energy.

→ Increase in the comet’s kinetic energy → increase in the comet’s velocity as it moves towards the sun.

→ As the comet moves away from the sun back to, its kinetic energy is converted into GPE.

→ Decrease in kinetic energy → decrease in comet’s velocity.


♦ Mean mark (a) 49%.

b.    As the speed of is constant, it must be travelling in a circular orbit.

→ and are both orbiting in a circle around their centre of mass.

→ Since both comets have the same mass, the radius of their circular motion is half of the distance between them.

As the centripetal force keeping in orbit is provided by the gravitational force acting on it due to :

 

 
 
 
 

PHYSICS, M7 2020 HSC 30b

  1. Calculate the wavelength of a proton travelling at 0.1.   (2 marks)
  1. Explain the relativistic effect on the wavelength of a proton travelling at 0.95.   (2 marks)
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i.   m

ii.  See Worked Solutions

Show Worked Solution
i.     
   
   

   

ii.    Due to momentum dilation:

→ The momentum of the proton is greater than that predicted by classical mechanics. 

→ Since 

→ The wavelength of the proton is shorter than would be predicted by classical mechanics.


♦ Mean mark (ii) 45%.

PHYSICS, M8 2020 HSC 30a

Explain, using an example, how a particle accelerator has provided evidence for the Standard Model of matter.   (3 marks)

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A linear accelerator used electric fields to accelerate electrons to very fast speeds and collide them with protons. The scattering of these electrons was analysed with technology and was inconsistent with protons being fundamental particles. The obtained data showed that protons contained both positive and negative internal charges. This observation contributed to the idea that protons were made up of quarks, and so provided evidence for the Standard Model of Matter.

 Answers could also mention:

→ Collision of protons accelerated to relativistic speeds at the LHC producing new, massive particles such as the Higgs-Boson hypothesised by the Standard Model of Matter. 

Show Worked Solution

A linear accelerator used electric fields to accelerate electrons to very fast speeds and collide them with protons. The scattering of these electrons was analysed with technology and was inconsistent with protons being fundamental particles. The obtained data showed that protons contained both positive and negative internal charges. This observation contributed to the idea that protons were made up of quarks, and so provided evidence for the Standard Model of Matter.

 Answers could also mention:

→ Collision of protons accelerated to relativistic speeds at the LHC producing new, massive particles such as the Higgs-Boson hypothesised by the Standard Model of Matter. 


♦ Mean mark 46%.

PHYSICS, M8 2021 HSC 35

A spacecraft is powered by a radioisotope generator. Pu-238 in the generator undergoes alpha decay, releasing energy. The decay is shown with the mass of each species in atomic mass units,

  1. Show that the energy released by one decay is  J.   (3 marks)
  1. At launch, the generator contains    atoms of Pu-238. The half-life of Pu-238 is 87.7 years.
  2. Calculate the total energy produced by the generator during the first ten years after launch.  (3 marks)
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Show Worked Solution

a.   

 
 

  

   

b.  


♦ Mean mark part (b) 51%.

BIOLOGY, M5 2021 HSC 12 MC

The graph shows the levels of three hormones, oestrogen, progesterone and human chorionic gonadotrophin (HCG), measured in the blood of a woman during her pregnancy.
 

Which statement can be inferred from the graph?

  1. Birth occurred about week 36.
  2. Fertilisation occurred at day 0.
  3. Implantation occurred about week 4.
  4. The placenta was formed about week 24.
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Show Worked Solution

→ HCG is released once the embryo has implanted.

→ Implantation occurs approximately 5-6 days after fertilisation which can take place when ovulation occurs, approximately 2 weeks after the menstrual cycle ends.

♦ Mean mark 49%.

CHEMISTRY, M5 2021 HSC 19 MC

A quantity of silver nitrate is added to 250.0 mL of 0.100 mol L ¯1 potassium sulfate at 298 K in order to produce a precipitate. Silver nitrate has a molar mass of 169.9 g mol ¯1.

What mass of silver nitrate will cause precipitation to start?

  1. 0.00510 g
  2. 0.186 g
  3. 0.465 g
  4. 0.854 g
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Show Worked Solution

The reaction when silver nitrate is added to potassium sulfate is:


 

Since each molecule has 1 sulfate ion


 


 

From the data sheet:


 


♦ Mean mark 45%.

CHEMISTRY, M8 2021 HSC 18 MC

The table lists the information from a proton NMR spectrum.
 

Which compound could have produced this spectrum?

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Show Worked Solution

By elimination:

There are 8 hydrogen atoms in total (3 + 3 + 2 = 8)

→ Eliminate A and C

Compound has a 3H singlet

→ Eliminate B


♦♦ Mean mark 39%.

CHEMISTRY, M8 2021 HSC 17 MC

A sample was contaminated with sodium phosphate. The sample was dissolved in water and added to an excess of acidified to produce a precipitate of .

If 24.21 g of dry was obtained, what was the mass of sodium phosphate in the original sample?

  1. 1.225 g
  2. 1.521 g
  3. 1.818 g
  4. 2.115 g
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Show Worked Solution
 
   
   

 
Each precipitate molecule has one molecule of

Each molecule has one molecule of

→  

→

 
   
   

 


♦♦ Mean mark 36%.

CHEMISTRY, M6 2021 HSC 16 MC

This titration curve is produced when an acid is titrated with a sodium hydroxide solution of the same concentration.

How many acidic protons does this acid possess?

  1. 1
  2. 2
  3. 3
  4. 4
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Show Worked Solution

From the graph there are 2 equivalence points (at ~ 10 mL and 20 mL), indicating that the acid is diprotic.

→ contains 2 acidic protons.


♦ Mean mark 39%.

CHEMISTRY, M6 2021 HSC 15 MC

What is the pH of the resultant solution after 20.0 mL of 0.20 mol is mixed with 20.0 mL of 0.50 mol ?

  1. 11.8
  2. 13.2
  3. 13.5
  4. 14.0
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Show Worked Solution

The reaction when  is mixed with is:

  ⟶

 
   
   

 

 
   
   

 
→ is the limiting reagent and is the excess reagent.

 
   
   

 

Therefore,

 
   
   

 


♦ Mean mark 54%.

CHEMISTRY, M8 2021 HSC 14 MC

A sample of nickel was dissolved in nitric acid to produce a solution with a volume of 50.00 mL. 10.00 mL of this solution was then diluted to 250.0 mL. This solution was subjected to colorimetric analysis. A calibration curve for this analysis is given.
 

The solution gave an absorbance value of 0.30.

What was the mass of the sample of nickel?

  1. 0.0021 g
  2. 0.031 g
  3. 0.053 g
  4. 0.15 g
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Show Worked Solution

Absorbance  = 0.30

From the calibration curve, an absorbance of 0.30 corresponds to a of .

 
   
   

 
This is the moles of in the diluted sample, which contained only 10.0 mL of the initial 50.0 mL of the original solution.

Thus, in order to find the number of moles in the original sample, multiply the number of moles by 5.

 
 
   
   
   

  


♦♦ Mean mark 38%.

CHEMISTRY, M8 2021 HSC 12 MC

The mass spectrum and carbon-13 NMR for an organic compound are shown.
 

 

Which compound could produce the two spectra?
 

 

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Show Worked Solution

→ The mass spectrum indicates that the m/z peak is at 98, indicating that the molecular mass of the substance is approximately 98.

→ Additionally, the C-13 NMR spectrum shows 4 signals indicating that there are 4 unique carbon environments.

→ Thus, only A has a molecular mass of 98 and fits the 4 unique carbon environments.


♦♦ Mean mark 35%.

PHYSICS, M6 2020 HSC 28

A metal rod sits on a pair of parallel metal rails, 20 cm apart, that are connected by a copper wire. The rails are at 30° to the horizontal.

The apparatus is in a uniform magnetic field of 1 T which is upward, perpendicular to the table.
 

A force, , is applied parallel to the rails to move the rod at a constant speed along the rails. The rod is moved a distance of 30 cm in 2.5 s.

  1. Show that the change in magnetic flux through the circuit while the rod is moving is approximately Wb.   (2 marks)
  1. Calculate the emf induced between the ends of the rod while it is moving, and state the direction of flow of the current in the circuit.   (2 marks)
  1. The experiment is repeated without the magnetic field.
  2. Explain why the force required to move the rod is different without the magnetic field.   (3 marks)
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a.    Wb

b.   

The direction of the induced current is anticlockwise as viewed from above.

c.   Explanation:

→ When the magnetic field is present, the induced current results in a force acting on the rod which opposes its motion (Lenz’s Law).

→ Additionally, the force required to move the rod must also overcome the downwards gravitational force.

→ Without the magnetic field, there is no opposing force due to the induced current so the force applied only needs to overcome gravity.

→ Hence, the force required to move the rod is less without the magnetic field.

Show Worked Solution
a.
   
   
    Wb

b.
   
   
    V  (V0)

  
The direction of the induced current is anticlockwise as viewed from above (Lenz’s Law).


♦ Mean mark (b) 51%.

c.   Explanation:

→ When the magnetic field is present, the induced current results in a force acting on the rod which opposes its motion (Lenz’s Law).

→ Additionally, the force required to move the rod must also overcome the downwards gravitational force.

→ Without the magnetic field, there is no opposing force due to the induced current so the force applied only needs to overcome gravity.

→ Hence, the force required to move the rod is less without the magnetic field.


♦ Mean mark (c) 50%.

PHYSICS, M7 2020 HSC 27

The following apparatus is used to investigate light interference using a double slit.
 

The distance, , from the slits to the screen can be varied. The adjustment screws vary the distance, , between the slits. The wavelength of the laser light can be varied across the visible spectrum. The diffraction pattern shown is for a specific wavelength of light.

Explain TWO methods of keeping the distance between the maxima at and constant when the wavelength of the laser light is reduced.   (4 marks)

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Decreasing the wavelength of light decreases the angular separation of the maxima.

To keep the distance between and constant:

→ Decrease the slit separation causing the angular separation to increase, compensating for the effect of decreasing . 

→ Increase the distance between the slits and the screen. This increases the linear distance between and , mitigating the effect of the reduction in .

Show Worked Solution

Decreasing the wavelength of light decreases the angular separation of the maxima.

To keep the distance between and constant:

→ Decrease the slit separation causing the angular separation to increase, compensating for the effect of decreasing . 

→ Increase the distance between the slits and the screen. This increases the linear distance between and , mitigating the effect of the reduction in .


♦ Mean mark 46%.

PHYSICS, M7 2020 HSC 26

  1. Describe the difference between the spectra of the light produced by a gas discharge tube and by an incandescent lamp.   (2 marks)
  1. The graph shows the curves predicted by two different models, and , for the electromagnetic radiation emitted by an object at a temperature of 5000 K.
     

    Identify an assumption of EACH model which determines the shape of its curve.   (2 marks)

  1. The diagram shows the radiation curve for a black body radiator at a temperature of 5000 K.
     


     
    On the same diagram, sketch a curve for a black body radiator at a temperature of 4000 K and explain the differences between the curves.   (4 marks)

Show Answers Only

a.   The spectra of light produced by a gas discharge tube will consist of lines only at a few discrete wavelengths.

The spectra of light produced by an incandescent lamp will be a continuous spectrum.

b.   Model black bodies absorb and emit energy continuously.

Model assumes that black bodies absorb and emit energy in discrete quantities.

c.


 
Using

Therefore, the 4000 K curve will have a peak wavelength greater than the 5000 K curve.

The area under the curve and the intensity at all wavelengths will be less for the 4000 K curve, as the total power output of a black body decreases as its temperature decreases.

Show Worked Solution

a.    Differences:

→ The spectra of light produced by a gas discharge tube will consist of lines only at a few discrete wavelengths.
→ The spectra of light produced by an incandescent lamp will be a continuous spectrum.


♦ Mean mark (a) 39%.

b.    Assumptions of EACH model:

→ Model black bodies absorb and emit energy continuously.
→ Model assumes that black bodies absorb and emit energy in discrete quantities.


♦ Mean mark (b) 44%.

c.

          

Using
Therefore, the 4000 K curve will have a peak wavelength greater than the 5000 K curve.
The area under the curve and the intensity at all wavelengths will be less for the 4000 K curve, as the total power output of a black body decreases as its temperature decreases.

PHYSICS, M8 2020 HSC 25

Describe the hydrogen atom in terms of the Standard Model of matter.   (4 marks)

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The hydrogen atom is composed of one proton in the nucleus and one orbiting electron.

  • The proton is a hadron comprised of three quarks, two up quarks each with charge    and one down quark with charge . These quarks are fundamental particles and are bound together by the strong nuclear force.
     
  • The electron is classified as a lepton and is a fundamental particle. It is held in its orbit by the electromagnetic force.
Show Worked Solution

The hydrogen atom is composed of one proton in the nucleus and one orbiting electron.

  • The proton is a hadron comprised of three quarks, two up quarks each with charge    and one down quark with charge . These quarks are fundamental particles and are bound together by the strong nuclear force.
      
  • The electron is classified as a lepton and is a fundamental particle. It is held in its orbit by the electromagnetic force.

♦ Mean mark 55%.

PHYSICS, M7 2020 HSC 22

A capsule travelling at 12 900 m s ¯1 enters Earth's atmosphere, causing it to rapidly slow down to 400 m s ¯1.

  1. During this re-entry, the capsule reaches a temperature of 3200 K.
  2. What is the peak wavelength of the light emitted by the capsule? (2 marks)
  1. Outline TWO limitations of applying special relativity to the analysis of the motion of the capsule.  (3 marks)
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a.    m

b.   Limitations:

→ The speed of the capsule is not close to the speed of light and so the effects of special relativity are insignificant.

→ The capsule is decelerating and so it is in a non-inertial frame of reference, therefore special relativity is not applicable.

Show Worked Solution
a.   
   
   
   

 

b.   Limitations:

→ The speed of the capsule is not close to the speed of light and so the effects of special relativity are insignificant.

→ The capsule is decelerating and so it is in a non-inertial frame of reference, therefore special relativity is not applicable.


♦ Mean mark (b) 42%.

PHYSICS, M5 2020 HSC 20 MC

The diagram shows a smooth, semi-circular, vertical wall with radius, .

A ball is launched from the position shown with a velocity towards north at an angle to the horizontal.
 

The ball follows a trajectory around the wall before landing on the ground, opposite its starting point. It does not reach the top of the wall.

Assume that there is no friction between the ball and the wall.

Which statement correctly describes the net force acting on the ball during its motion?

  1. The magnitude of the net force remains constant.
  2. The direction of the net force is vertically downwards.
  3. The direction of the net force is perpendicular to the wall.
  4. The magnitude of the net force reaches a minimum when the ball is at its highest point.
Show Answers Only

Show Worked Solution

The ball experiences a constant, downwards acting weight force.

The ball also experiences a centripetal force with constant magnitude due to its constant horizontal speed, perpendicular to its weight.

→ Since both forces are always perpendicular, the magnitude of the net force on the ball remains constant.


♦ Mean mark 31%.

PHYSICS, M6 2020 HSC 14 MC

Two parallel wires, and , each carry a current .
 

The magnitude and direction of the force on wire are represented by the vector .

The current in wire is then doubled and its direction is reversed. The current in wire remains unchanged.

Which vector arrow represents the force on wire after the change to the current in wire ?
 

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Show Worked Solution

Reversal of current in   → attractive force between wires.

Doubling of the magnitude of current in → doubling of the magnitude of force (Ampere’s Law)


♦ Mean mark 43%.

PHYSICS, M7 2020 HSC 13 MC

The graph shows the relationship between the frequency of light used to irradiate two different metals, and the maximum kinetic energy of photoelectrons emitted.
 


 

Suppose that light having a frequency of Hz is used to irradiate both metals.

Compared to the photoelectrons emitted from metal , photoelectrons emitted from metal will

  1. have a lower maximum velocity.
  2. have a higher maximum velocity.
  3. take a longer time to gain sufficient energy to be ejected.
  4. take a shorter time to gain sufficient energy to be ejected.
Show Answers Only

Show Worked Solution

The graph shows photoelectrons emitted from metal have a lower maximum kinetic energy

→ they have a lower maximum velocity.

The time taken for photoelectrons to gain sufficient energy to be ejected is the same for both metals.


♦ Mean mark 49%.

PHYSICS, M6 2020 HSC 10 MC

An electron travelling in a straight line with an initial velocity, , enters a region between two charged plates in which there is an electric field causing it to travel along the path as shown.
 

A magnetic field is then applied causing a second electron with the same initial velocity to pass through undeflected.

Which row of the table shows the directions of the electric and magnetic fields when the second electron enters the region between the plates?

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Show Worked Solution

The bottom plate is positively charged as it attracts the electron.

→ Electric field is towards the top of the page.

Using the right hand palm rule, the magnetic field must be out of the page to produce an upwards force on the electron.


♦ Mean mark 50%.

PHYSICS, M8 2020 HSC 6 MC

The Hertzsprung-Russell diagram shows characteristics of stars in a globular cluster 100 light years in diameter and 27 000 light years from Earth.
 

The stars plotted on this Hertzsprung-Russell diagram have approximately the same

  1. age.
  2. colour.
  3. luminosity.
  4. mass.
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Show Worked Solution

The -axis indicates the stars have varying colour and mass.

The -axis indicates the stars vary in luminosity. These variations indicate the stars also vary in mass.

The fact that the stars are found in a cluster suggests they are of a similar age.


♦ Mean mark 41%.

PHYSICS, M7 2021 HSC 33

Two experiments are performed with identical light sources having a wavelength of 400 nm.

In experiment , the light is incident on a pair of narrow slits  m  apart, producing a pattern on a screen located 3.0 m behind the slits.
 

In experiment , the light is incident on different metal samples inside an evacuated tube as shown. The kinetic energy of any emitted photoelectrons can be measured.
 

Some results from experiment are shown.
 

How do the results from Experiment and Experiment support TWO different models of light? In your answer, include a quantitative analysis of each experiment.   (9 marks)

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→ Experiment A supports the wave model of light as it demonstrates light undergoing diffraction as well as constructive and destructive interference, which are wave properties.

→ When light is incident upon the slits, it diffracts and causes the slit to act as a source of wavefronts. When light from the slits arrives at the screen, bright bands are produced when light waves arrive in phase and undergo constructive interference.

→ Dark bands are produced when light waves arrive at the screen out of phase and undergo destructive interference.

→ The spacing between adjacent bright bands can be calculated:

             
 
 
 

 
→ Experiment B supports Einstein’s particle, or photon model of light. This model can calculate the photon energy of incident light and explain why photons are emitted from calcium but not nickel:


 

→ This energy is greater than the work function of calcium, explaining why one photon has enough energy to liberate a photoelectron from the calcium sample. However, this energy is less than the work function of nickel, explaining why no photoelectrons were observed from the nickel sample.

→ These observations support the particle model of light. Applying the particle model, the kinetic energy of photoelectrons emitted from calcium can be calculated:

Show Worked Solution

→ Experiment A supports the wave model of light as it demonstrates light undergoing diffraction as well as constructive and destructive interference, which are wave properties.

→ When light is incident upon the slits, it diffracts and causes the slit to act as a source of wavefronts. When light from the slits arrives at the screen, bright bands are produced when light waves arrive in phase and undergo constructive interference.

→ Dark bands are produced when light waves arrive at the screen out of phase and undergo destructive interference.

→ The spacing between adjacent bright bands can be calculated:

             
 
 
 

 
→ Experiment B supports Einstein’s particle, or photon model of light. This model can calculate the photon energy of incident light and explain why photons are emitted from calcium but not nickel:


 

→ This energy is greater than the work function of calcium, explaining why one photon has enough energy to liberate a photoelectron from the calcium sample. However, this energy is less than the work function of nickel, explaining why no photoelectrons were observed from the nickel sample.

→ These observations support the particle model of light. Applying the particle model, the kinetic energy of photoelectrons emitted from calcium can be calculated:


♦ Mean mark 52%.

PHYSICS, M8 2021 HSC 32

Two students perform an investigation with a piece of elastic laid out straight on a table. The elastic is fixed at one end and has three markings at regular intervals. The distances from each marking to the fixed end, and , are measured as shown.
 

A student pulls the elastic to extend it, and the new values of and are measured. The student observes that each value has doubled.

How well do the observations from this investigation model the evidence that led to Hubble's discovery of the expansion of the universe? Justify your answer.   (5 marks)

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→ Hubble observed that galaxies further away from Earth are receding at a faster rate that is proportional to their distance from Earth.

→ From this he discovered that space is expanding.

→ The investigation successfully models this as markings further away from the fixed end moved by a larger amount as the elastic expands.

→ This increase is proportional to a marking’s distance from the fixed end and links to the greater recessional velocity of more distant galaxies.
 

Limitations:

→ The elastic only expands in one direction whereas Hubble’s evidence demonstrated that the universe is expanding in three dimensions.

→ The investigation measures the change in the position of markings whereas Hubble measured speed of galaxies.

→ The markings themselves stretch. Hubble didn’t find that the galaxies themselves were spreading out.

Show Worked Solution

→ Hubble observed that galaxies further away from Earth are receding at a faster rate that is proportional to their distance from Earth.

→ From this he discovered that space is expanding.

→ The investigation successfully models this as markings further away from the fixed end moved by a larger amount as the elastic expands.

→ This increase is proportional to a marking’s distance from the fixed end and links to the greater recessional velocity of more distant galaxies.
 

Limitations:

→ The elastic only expands in one direction whereas Hubble’s evidence demonstrated that the universe is expanding in three dimensions.

→ The investigation measures the change in the position of markings whereas Hubble measured speed of galaxies.

→ The markings themselves stretch. Hubble didn’t find that the galaxies themselves were spreading out.


♦ Mean mark 51%.

PHYSICS, M6 2021 HSC 31

Two identical solenoids are mounted on carts as shown. Each solenoid is connected to a galvanometer, and the solenoid on cart 1 is also connected to an open switch and a battery. The total mass of cart 1 is twice that of cart 2.
 

Explain what would be observed when the switch on cart 1 is closed. In your answer, refer to the current in each galvanometer and the initial movement of the carts.   (7 marks)

Show Answers Only

When the switch on cart one is closed, a direct current will flow through the cart 1 solenoid causing a deflection on

Using the right hand grip rule, this will create a magnetic field with a south pole on the right hand side of this solenoid. As this magnetic field is generated, the solenoid on cart two experiences a change in magnetic flux.

According to Faraday’s law, an induced emf and current will be generated in the cart 2 solenoid.

By Lenz’s law, this current will flow in a direction that opposes the original change in flux, causing a magnetic south pole on the left hand side of this solenoid, and a momentary deflection of in the opposite direction to .

As the two solenoids produce south poles facing each other, they will repel causing the carts to move away from each other. The law of conservation of momentum dictates that since cart 1 is double the mass of cart 2, it will have half the velocity of cart 2.

Show Worked Solution

When the switch on cart one is closed, a direct current will flow through the cart 1 solenoid causing a deflection on

Using the right hand grip rule, this will create a magnetic field with a south pole on the right hand side of this solenoid. As this magnetic field is generated, the solenoid on cart two experiences a change in magnetic flux.

According to Faraday’s law, an induced emf and current will be generated in the cart 2 solenoid.

By Lenz’s law, this current will flow in a direction that opposes the original change in flux, causing a magnetic south pole on the left hand side of this solenoid, and a momentary deflection of in the opposite direction to .

As the two solenoids produce south poles facing each other, they will repel causing the carts to move away from each other. The law of conservation of momentum dictates that since cart 1 is double the mass of cart 2, it will have half the velocity of cart 2.


♦ Mean mark 45%.

PHYSICS, M8 2021 HSC 29

Bohr, de Broglie and Schrödinger EACH proposed a model for the structure of the atom.

How does the nature of the electron proposed in each of the three models differ?   (5 marks)

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Bohr’s model of the atom proposed that the electron was a negatively charged particle which orbits the nucleus in a circular path at discrete, quantised energy levels.

De Broglie’s model proposed that electrons had a dual wave/particle nature existing as stable standing waves around the nucleus.

Schrödinger’s quantum mechanical model described electrons as having a wave nature and existing as orbitals. His equation described a cloud surrounding the nucleus in which electrons had a high probability to be found.

Show Worked Solution

Bohr’s model of the atom proposed that the electron was a negatively charged particle which orbits the nucleus in a circular path at discrete, quantised energy levels.

De Broglie’s model proposed that electrons had a dual wave-particle nature existing as stable standing waves around the nucleus.

Schrödinger’s quantum mechanical model described electrons as having a wave nature and existing as orbitals. His equation described a cloud surrounding the nucleus in which electrons had a high probability to be found.


♦ Mean mark 49%.

PHYSICS, M7 2021 HSC 28

A spaceship travels to a distant star at a constant speed, . When it arrives, 15 years have passed on Earth but 9.4 years have passed for an astronaut on the spaceship.

  1. What is the distance to the star as measured by an observer on Earth?   (3 marks)
  1. Outline how special relativity imposes a limitation on the maximum velocity of the spaceship.  (2 marks)
Show Answers Only
  1.   12 ly
  2.   According to special relativity, as → :
  3.   → the momentum of the spaceship approaches infinity
  4.   → the force required to accelerate the spaceship approaches infinity
  5.   → maximum velocity is limited to the speed of light.
Show Worked Solution

a.   

 
 
 
 

  
Distance to star from Earth observer:

 
   
   

♦ Mean mark part (a) 51%.

b.  According to special relativity, as → :

→ the momentum of the spaceship approaches infinity

→ the force required to accelerate the spaceship approaches infinity

→ maximum velocity is limited to the speed of light.

PHYSICS, M8 2021 HSC 19 MC

Rh-106 is a metallic, beta-emitting radioisotope with a half-life of 30 seconds.

A sample of Rh-106 and an electrode are placed inside an evacuated chamber. They are connected to a galvanometer and a variable DC power supply.
 

A student measures the current, , when the power supply is set to zero. They then measure the stopping voltage, . The stopping voltage is the minimum voltage needed to prevent current flowing.

A few minutes later, these measurements are repeated.

How do the TWO sets of measurements compare?

  1. Only changes.
  2. Only changes.
  3. Both and change.
  4. Neither nor changes.
Show Answers Only

Show Worked Solution

Due to the short half life of the isotope, there will be significantly less present when the second reading is made.

→ Lower rate of emission of electrons → Lower recorded current

The energy of emitted electrons will remain the same → Voltage will not change


♦ Mean mark 29%.

PHYSICS, M6 2021 HSC 18 MC

An evacuated chamber contains a pair of parallel plates connected to a power supply and a switch which is initially closed.

A positively charged mass (•) falls within the chamber, under the influence of gravity, from the position shown.
 

When the mass has fallen half the height of the chamber, the switch is opened.

Which of the following correctly shows the trajectory of the mass?
 

 

Show Answers Only

Show Worked Solution

The mass experiences a constant force to the right due to the electric field and a constant force downwards due to gravity.

This results in a net force pointing diagonally down and to the right. The mass travels in the direction of this net force.

When the switch is opened the mass falls only under the influence of gravity, following a parabolic path.


♦ Mean mark 35%.

PHYSICS, M6 2021 HSC 17 MC

Two long, parallel conductors and are connected to a light bulb and an AC power supply. The conductors are suspended horizontally from fixed points using sensitive spring balances. is positioned directly below .
 


 

Which statement correctly compares the forces measured by the spring balances?

  1. The forces measured on and will always be equal.
  2. The force measured on will be greater than or equal to that on .
  3. The force measured on will be greater than or equal to that on .
  4. There will be a continuous reversal of which measured force is greater.
Show Answers Only

Show Worked Solution

Current in wires in opposite direction → The two conductors will always repel (Ampere’s Law)

Resulting forces:

→ upwards force on Y which partially cancels its weight, decreasing the net downwards force acting on it

→ downwards force on X which increases the net downwards force acting on it.


♦ Mean mark 23%.

PHYSICS, M7 2021 HSC 15 MC

Unpolarised light is incident upon two consecutive polarisers as shown. The second polariser has a fixed transmission axis which cannot be rotated.  is the intensity of light after the first polariser, and  is the intensity of light after the second polariser.
 

How would and  be affected if the transmission axis of the first polariser was rotated?

  1. Both would change.
  2. Only  would change.
  3. Only  would change.
  4. Neither would change.
Show Answers Only

Show Worked Solution

  is constant at 50% of the original intensity.

  varies depending on the angle between the two polarisers (Malus’ Law).


♦ Mean mark 42%.

PHYSICS, M5 2021 HSC 9 MC

A mass, , is positioned at an equal distance from two identical stars as shown.

The mass is then moved to position .
 

Which graph best represents the gravitational potential energy, , of the mass during this movement?
 

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Show Worked Solution

Potential energy decreases as the mass moves closer to the stars and then increases as it moves away from them.


♦ Mean mark 43%.

PHYSICS, M6 2021 HSC 7 MC

In a certain ideal transformer, the current in the secondary coil is four times as large as the current in the primary coil.

Which row of the table correctly identifies the type of transformer and the ratio of turns?

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Show Worked Solution

Larger current in secondary coil → Lower voltage in secondary coil

→ Step down transformer → Primary coil has more turns


♦ Mean mark 42%.