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  1. Rathaen

    Answers wrong in Dot Point 1.11.1 'Moving About' ?

    Well normally you'd integrate the function of velocity with respect to time, but since this is HSC I assume you'll just sort of fudge it and visually examine how many squares and little triangle bits are underneath and then estimate the area. Hence the answer being given as "about 390".
  2. Rathaen

    Answers wrong in Dot Point 1.11.1 'Moving About' ?

    If you look at the graph, you'll notice the velocity on time graph is not a straight line. This means that the car is undergoing non uniform linear motion, or in other words it doesn't have a constant acceleration, and this is the reason your answer is wrong. (because your kinematics equations...
  3. Rathaen

    Quanta Vs Astrophysics REVIEW PLZ

    Whether or not you get to choose your electives depends on your teachers. Personally I preferred quanta to quarks but that might just be because I never really paid attention to anything other than what we were learning.
  4. Rathaen

    Decimal Places

    That'll be because 2.0 is effectively stating that the digit in the first decimal place is 0. If you were to simply have 2, that could mean anywhere between 1.5 and 2.5, assuming rounding. 2.0 would imply a greater amount of accuracy which would mean that the actual number is somewhere around...
  5. Rathaen

    Iron Carbide Phase Diagram

    From memory, you need to know up to about 1800 degrees C on the diagram, and be able to explain what is happening as it cools or heats up at various points in that section. This means the section from the origin up to the solid austenitic range and out to about 3 or 4% where you start getting...
  6. Rathaen

    Question regarding point charge and charged metal plate? - Multi choice

    Just to clarify on question 8, the answer is C because field lines for electric charges always point in the direction that a positive charge would move if placed in the field. Thus away from the positive charge, and towards the negatively charged plate.
  7. Rathaen

    force and torque in motors?

    The force on the coil is constant from F=BILsin(theta) because the sides of a square coil will be perpendicular to the magnetic field (with magnets on either side). The torque, however will be different, because the force on each side of the coil changes distance relative to the pivot point of...
  8. Rathaen

    Preliminary Physics Question: Types of Waves

    Yep, B is definitely correct, and your reasoning is right too. For the explosion, the noise is sound, which is also a pressure wave. This wave is created by the force of the explosion (expanding gases), and travels outwards from the explosion. You hear the sound when the pressure wave reaches...
  9. Rathaen

    Force and Newton's three laws of motion questions

    When you hit the brakes, the friction from the brakes slows down the car wheels, which slows down the car from the friction generated between the car wheels and the road surface. In normal car brake operation, the wheels never actually stop rotating until the car comes to a stop. This means that...
  10. Rathaen

    Prelim Physics Question Moving About

    Well how many marks is this question? From the way you've outlined it, you've pretty much already answered what the question is asking. The stopwatch is a better timekeeping device than simply counting, and has advantages over a normal watch or clock in that you can start and stop it, but errors...
  11. Rathaen

    HELP on Motor assignment

    If carbon brushes are unavailable, you can use paperclip or thick metal wire bent partially around your commutator. Anything that conducts electricity and will allow the commutator to rotate while maintaining electrical contact will be fine.
  12. Rathaen

    What does your desk look like?

    My desk actually tends to clear up just before exam times. Before exams, it gets cluttered with all these random notes and papers, and then when I actually need to study I end up clearing everything into neat stacks on the floor so that I can have one or two notebooks on my table to focus on.
  13. Rathaen

    Explain what these extracts mean (China case study)

    Main point here is urbanisation, which is basically more people moving to urban areas (towns, cities) from rural areas. Presumably this relates to the improving of agricultural productivity in that the industry is then shifting to more efficient production processes (via technology, allowing...
  14. Rathaen

    Real interest rates

    Well if I remember this right, the RBA sets their inflation goal for underlying inflation (ie. they want to keep underlying inflation at 2-3%), but when conducting DMOs, they react to headline CPI. This is because if you think about it, since underlying is pretty much the average of headline...
  15. Rathaen

    Engineering Question/Answer Textbook/Website Source Recommendations?

    Well, I used Rochford's Student Workbook this year, along with Copeland (Guide to Engineering?), and Excel HSC Engineering, and those three are pretty similar in terms of depth. They all contain some stuff that the other three don't, but they're all concise and cover pretty much everything you...
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