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  1. D

    BoS Trials Maths, Physics and Business Studies 2023

    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 I_x and I_y do not make sense. The problem is that the electric field due to the x and...
  2. D

    BoS Trials Maths, Physics and Business Studies 2023

    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...
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    Mathematics Extension 1 HSC thoughts

    The constant solutions are asymptotes, so your solution cannot be correct.
  4. D

    Mathematics Extension 1 HSC thoughts

    I did the approach that 011235 mentions, but got the same answer as you the first time, 358. 402 seems much too large to be plausible if it's 95% chance someone will turn up.
  5. D

    Mathematics Extension 1 HSC thoughts

    Prove u - p is perpendicular to v with dot product. Let q be any point on v i.e. q = lambda v. Then by pythagoreas |u-p|^2 + |p-q|^2 = |u-q|^2. So |u-q|^2 >= |u-p|^2 and sub in with lambdas
  6. D

    Mathematics Extension 1 HSC thoughts

    I believe 6 C is incorrect, it should be B (see above).
  7. D

    Mathematics Extension 1 HSC thoughts

    Also the diagram was 'DRAWN TO SCALE', so 3.2 is much too large.
  8. D

    Mathematics Extension 1 HSC thoughts

    If you consider f(x)= x^3 and its inverse, the intersection at the origin has the tangents to the graph be perpendicular. So D is also incorrect? Edit: I realised that a vertical tangent means it f'(x) is not defined for the inverse for all real x.
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    Mathematics Extension 1 HSC thoughts

    Did anyone get the actual answer for 14c?
  10. D

    Mathematics Extension 1 HSC thoughts

    I belive it's B because the constant solutions are asymptotes of a particular solution. So -pi/2 and 3pi/2.
  11. D

    Maths Extension 2 Thoughts and Feelings

    On the way down, the velocity is negative (as you define upwards as positive). In this case, an 'resistive force' of 0.1v is still negative i.e. in the same direction as the velocity. So your resistive force is pushing the mass down when it should be pushing it up. You should have a = -g - 0.1v...
  12. D

    Maths Extension 2 Thoughts and Feelings

    I graphed the x function and the axis of symmetry is around 3.3 (using v_0 = 39.1), not quite 3.5. So the solution is valid, with the time to fall longer than the time to go up.
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    Maths Extension 2 Thoughts and Feelings

    This is what I thought in the exam (to my demise as I made some algebraic errors), but I think the change in sign of the velocity accounts for this change in direction. You end up with the same answer nonetheless (if you don't screw up like I did).
  14. D

    BoS trials Maths and Chemistry 2022

    [/QUOTE Is this something you would be penalised for in the HSC? If so, what is the best way to avoid this?
  15. D

    BoS trials Maths and Chemistry 2022

    Thanks so much! I never would have thought of that first step.
  16. D

    BoS trials Maths and Chemistry 2022

    How do you do Q11e of 4U?
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