BoS Trials Maths, Physics and Business Studies 2023 (4 Viewers)

[Zombie1122334]

Boom! Business Studies results and the marking criteria/sample answers are attached below!

Thank you to everyone who attended to the event and attempted the paper. Congrats to the top student who scored 88 in the paper!

Thanks heaps to @jimmysmith560 for helping to write the paper and marking the student responses.

Please note that the question paper has been updated mainly to remove some ambiguities in the question structures (which were taken into account when marking). The updated file is attached in my original post of the papers to replace the older version.

We're still working on Physics so please watch this space...

Can we get physics please?

 

[Lupa]

Has phys solutions been posted yet?

 

[carrotsss]

Has phys solutions been posted yet?

Not yet

 

[CatherineMarie]

I was just about to ask about the solutions

 

[scaryshark09]

dw, i can write the solutions up for ya'll rn

 

[WeiWeiMan]

dw, i can write the solutions up for ya'll rn

knock urself out

 

[CatherineMarie]

*sigh*

 

[Trebla]

... and finally what you all have been waiting for

Here are the marking guidelines and sample answers for Physics!

Thank you for your patience.

Please also note that the question paper has been updated (which these solutions are aligned to) with some minor adjustments to a few questions (e.g. edited some wordings and mark allocations). The updated file is attached in my original post of the papers to replace the older version.

FYI the marking is almost done, just need to tie up a loose end which we hope to resolve soon. Once, that is done we can release the results and wrap the whole thing up for another year.

 

[Daedalus13]

Thanks to everyone who sat the inaugural BoS Physics Trial! I hope that everyone enjoyed these questions (or at least found them helpful) in preparation for the coming HSC exam.

Below are some thoughts I had during the marking of Section 2 Booklet 1.

General

• Use words! You can’t explain something properly using only symbols and shorthand especially if you don’t explain what those symbols mean
• Even in calculations, write words to explain what you’re doing, otherwise if you just write (incorrect) numbers, I can’t give any marks
• Don’t leave longer answer questions blank - you can easily pick up 2–3 marks just by mentioning key words and ideas, especially compared to calculations
• Leading on from the previous point, plan your time well - it's better to half-answer 4 questions than over-answer 1 question

Question 21

• Some students attempted to use the formula for orbital velocity, however, this is not valid for elliptical orbits. Although the HSC will never require anything more than a basic knowledge of conics, it is vital to know the assumptions made to derive equations and the situations in which they are valid

Question 22(c)

• Many students incorrectly assumed that the friction force was constant, but it depends on Φ

Question 23

• Many students spent the whole questions analysing why step-up transformers are used, which was good, however, this was not enough to gain full marks
  • This question was generally answered poorly with lots of superfluous information - make sure you read the question
• The mark allocation on this question should give a hint as to how much detail is required - you needed to also explain how the power loss is reduced in that step-up transformer
• Students should also note the difference between P = I^2 R, the power dissipated by a resistor, and P = IV, the power generated in a circuit
• ‘Equations’ implies at least two
• Equations should be integrated correctly - way too many students thought that V = IR means that increasing voltage decreases current???

Question 24(a)

• There were two parts to this claim
  • The time difference
  • The explanation using time dilation
• Most students only assessed the first part, but did not justify why time dilation cannot be used to analyse this situation

Question 25(a)

• It was extremely surprising to see many students think that aluminium is a better conductor than copper despite almost all circuits being built from copper wires

Question 25(b)

• Faraday’s Law does not (directly) cause current only EMF
• Students should explain why the graph in the metal sections is linear / constant velocity rather than just ‘it slows down’ - it technically isn’t slowing down just moving at a constant velocity so this is wrong
  • Additionally, the magnetic force on the magnet is the same in both copper and aluminium since it is balancing gravity
• Must apply conservation of energy explicitly (“Since energy must be conserved …”) rather than just describing energy transformations (they can still happen if energy is not conserved)
• If numbers are given, do a quantitative analysis, however, this was not penalised
• Comparing three things is not the same as describing three things - use words like “similar to …”, “unlike …”, or even as simple as “more than” or “less than”

Question 26

• Many students seem to have misconceptions about the nature of polarisation
  • Polarisation is a vector quantity that obeys superposition so any (constant) mix of polarisation directions can be reduced to its x and y components which is hence linear (assuming no phase difference) NOT unpolarised
• This question is conceptually very difficult and nuanced, and almost no student made the correct judgement. It was instead marked based on how well you were able to justify the claim you made, even if it was incorrect
  • If you make a claim, ensure your argument is consistent by referring to the statement as valid, invalid or somewhat valid throughout
  • If your argument doesn’t make sense to you, it’s probably wrong
  • It’s very bad if I still don’t know whether you think the claim is valid or not after reading your whole response
  • Engage with the actual statement - some students simply explained what they thought unpolarised light is, without making a judgement of the original statement

Question 27(c)

• Not a single student noticed the difference between Φ and θ!!!
• A number of students attempted to use E = hf = hc/lambda as the kinetic energy of the electrons - clearly electrons are not massless particles moving at the speed of light and this is invalid
• It was good to see students who could not do part (a) simply apply d sin(theta) = m lambda and gain ECF marks

 

[Sam14113]

Thanks for providing solutions! Can I just ask for the polarisation question to be clarified please (Q26)?

If we assume 50% of light is polarised in x direction and 50% polarised in y direction, then I would think we get the following equations when passed through a polariser:





Which is the behaviour we do get with unpolarised light.

The answers, however, say the following:
If the unpolarised light was comprised of a constant mix of x and y polarisations, the intensity is expected to vary with the angle that the polarisation axis makes with the vector sum of the x and y polarisations, by Malus’s Law.
This contradicts my working, and so either the answer is incorrect or my working is incorrect. I am inclined to believe the latter.
Can someone please explain to me where I have gone wrong?
Thank you

 

[Jiefu Lu]

Thanks to everyone who sat the first ever BoS Phys Trial!!

I was responsible for most of the questions of Section 2 Booklet 2 sorry not sorry !!
discord: @metara if you have any questions

 

[Daedalus13]

Thanks for providing solutions! Can I just ask for the polarisation question to be clarified please (Q26)?

If we assume 50% of light is polarised in x direction and 50% polarised in y direction, then I would think we get the following equations when passed through a polariser:





Which is the behaviour we do get with unpolarised light.

The answers, however, say the following:
If the unpolarised light was comprised of a constant mix of x and y polarisations, the intensity is expected to vary with the angle that the polarisation axis makes with the vector sum of the x and y polarisations, by Malus’s Law.
This contradicts my working, and so either the answer is incorrect or my working is incorrect. I am inclined to believe the latter.
Can someone please explain to me where I have gone wrong?
Thank you

Thanks for bringing this up, because it is a common mistake that arises when students don't respect the differences between scalars and vectors. Firstly, remember that intensity is not a vector quantity, so and do not make sense. The problem is that the electric field due to the x and y-components cancel, so you can't just add their intensities separately. See the working below:

 

[Zombie1122334]

Thanks to everyone who sat the first ever BoS Phys Trial!!

I was responsible for most of the questions of Section 2 Booklet 2 sorry not sorry !!
discord: @metara if you have any questions

brother who are you if you didn't get 99.95 I am disappointed.

 

[carrotsss]

brother who are you if you didn't get 99.95 I am disappointed.

he got a 99.85 despite getting 3 state ranks

 

[Zombie1122334]

he got a 99.85 despite getting 3 state ranks

Bruh i have no hope of getting band 6 now

 

[oml]

@jimmysmith560 will there be a business studies trial next yr?

 

[its_ace21]

@jimmysmith560 will there be a business studies trial next yr?

yea im gonna write it

 

[scaryshark09]

he got a 99.85 despite getting 3 state ranks

did english play into this?

 

[jimmysmith560]

@jimmysmith560 will there be a business studies trial next yr?

I hope so

 

[carrotsss]

did english play into this?

yeah

i know this because whenever i stalk tutoring results pages to find state rank cutoffs hes always on the lists lmao, he didn't b6 english though according to hscninja so im assuming thats why