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  1. Rachaek

    photoelectric effect

    With the photoelectric effect they found that only light above a specific frequency (threshold frequency) would eject electrons from the metal, regardless of the intensity of the light or the time the metal was exposed. The wave model predicted that if the metal was exposed to light for a...
  2. Rachaek

    Galvanic Cell Salt Bridge

    yeah, basically how I understand it is that the electron move around the external circuit from one cell to the other. Since all the electrons are moving to one cell, this cell becomes negatively charged, and the other positive. The ions in the solution then move to counteract this buildup of...
  3. Rachaek

    Rubics Cube

    I can solve them, a friend taught me. I wish I could've solved it through logic/maths, but mostly it is just remembering algorithms with not much thinking involved. Anyway, quite fun to do when you're bored, but once solved a few times its only useful for finger exercising rather than brain...
  4. Rachaek

    Hi, anyone know where I can find a copy of the 2008 math HSC paper

    http://community.boredofstudies.org/showthread.php?t=189247 There is a downloadable copy here =)
  5. Rachaek

    Post Prac-Exam Query

    I think you only found the KJ released through combustion of your 0.6g of ethanol, rather than the KJ per mole provided you used 100mL of water h= m x c x change in temp = 100 x 4.18 x 21.5 = 8987 J (which is the amount of energy released by combustion of 0.6g of ethanol, not one mole) to find...
  6. Rachaek

    what is allowed in projectile motion calculations?

    Technically you are 'allowed' to use the maths method to solve the physics questions, in that if you get the right answer you will get your marks (or so I am told). However, you are not 'allowed' to use the physics method for maths, and will get no marks (or few marks) regardless of whether your...
  7. Rachaek

    What's The Best Way To Check Answers In Exams When Finished Early?

    Most questions in Q1 section of the paper and others can be checked so that you can be absolutely sure you have the correct answer. Any rearraging, simplifying, factorising etc. questions I always just substitute in a value for the pronumeral, and check that both sides remain equal, or with...
  8. Rachaek

    cyclic quad question

    Yep, I'm pretty sure it is a cyclic quadrilateral. As you say, angles in the same segment are equal. Since this is a property shown by points lying on the circumference of a circle, it can be said that these points are concyclic (ie. form a cyclic quadrilateral) also, it says on wikipedia...
  9. Rachaek

    [URGENT!!!!] Projectile Motion Prac!!!

    We once did a prac in class involving rolling steel balls off the end of a ramp, then set up a vertical barrier with carbon paper to determine how far each ball travelled or fell (vertically). We then analysed the results (as separate vertical and horizontal components) to find the velocity of...
  10. Rachaek

    Enzyme use for PLA???

    I had these as the steps for creating PLA: - Corn milled to separate out the starch - Alpha amylase enzyme breaks down starch molecules - Glucoamylase breaks molecules down further into glucose - Glucose fermented to produce lactic acid - Condensation reaction to join two lactic...
  11. Rachaek

    Help!! w/ Michelson-Morley

    Yep, straight from syllabus, therefore important =) Here is some info straight from my notes, hope it helps: (1) Describe and evaluate the Michelson-Morley attempt to measure the relative velocity of the Earth through the aether - Aim was to measure the earth’s speed relative to the aether...
  12. Rachaek

    assumptions/commonly held views about the journey

    Ahaha yeah I'm stuck on that one too! I saw the topic and was like hey, we need to know that too. It says "if applicable" for that point so I'm just going to think its not applicable. I'm so stuck for an oral text arghh!
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