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  1. K

    Relative Difficulty

    Not including the Optional Units, it was more difficult than 2009 and 2011, but less difficult than 2010 IMO.
  2. K

    Astrophysics - Discuss Questions!

    It depends. It was worth four marks. So they'll probably be looking for the device used for each, including brief mention to how they work (2mks). And then the information each is used to collect (1mk). And what that information is used to do (1mk). So, if you didn't mention...
  3. K

    raw mark

    Felt good until I hopped on this forum and realised I kooked the Tower question, 1/4 maybe. Lost a mark or two explaining the loudspeaker. Lost a mark or two in multiple choice. Probably drop a few marks due to unforeseen variables. Astrophysics was too easy IMO, was hoping for lengthy...
  4. K

    Section I - Multiple Choice

    +1. Word for word what I was going to post. I still think it's A. Even if the BoS says it's B, I still think it's A. I mean, what if we're trying to detect thermal radiation from a particularly cold person (he's been plowing the snow fields of siberia). Peak wavelength would be down and to the...
  5. K

    Astrophysics - Discuss Questions!

    - I identified that it was an eclipsing binary, therefore plane of orbit was in line with line of sight. - Identified Star A as the brighter of the two, which caused the large brightness dip when it was eclipsed by the smaller star. - I calculated the mass of the system - Identified the star...
  6. K

    That tower question

    That doesn't make sense. The earth's rotational velocity has nothing to do with a satellites orbital velocity (V = sqrt(GM/r). Orbital velocity would be produced by the inward acceleration due to gravity, as gravity is a centripetal force. Both satellites have the same orbital period (of 24...
  7. K

    Physics marathon (hsc)

    Oh man. As far as I've seen you know your shit, so I'm inclined to trust what you're saying. Although, as far as I knew the Meissner Effect was separate, totally different thing, to induced magnetic fields. - From wikipedia Edit: I mean, eddy currents will be induced, however they do not have...
  8. K

    Physics marathon (hsc)

    Meisner effect is separate from eddy currents. No. The change in flux that occurs should in fact resist the change which caused it. Hence it should actually resist the magnet's levitation.
  9. K

    Anyone up for a Astrophysics Marathon?

    Correct. However, you may want to review the wording of the last part.
  10. K

    Thought Experiment

    If no reflection, or a delayed reflection was produced you would know that you are travelling at a certain velocity without referring to an external frame of reference, as this violates the principle of relativity, it cannot be possible. Thus you must see a reflection in normal time. However...
  11. K

    Group 3/5 elements

    Count in columns from the left, disregard the transitional metals (i.e. purple columns). The one starting with Boron is GIII
  12. K

    Anyone up for a Astrophysics Marathon?

    Explain why a white dwarf does not collapse further. (2mks)
  13. K

    Transistors...switches and/or amplifiers?

    I'm a bit fuzzy on transistors, but I'll give it a shot. They don't really amplify the current, they just act as a valve, which allows more current to pass through the circuit. They replaced thermionic valves right? They do the exact same thing, just in a different manner. Basically what...
  14. K

    Okay, I have a few questions...

    Maximum flux is when the coil is perpendicular to the magnetic field. But induced emf isn't about the amount of flux threading the coils, it's about the rate of change of flux through the coils. The rate of change of flux is at maximum where flux is at zero. (i.e. emf is equal to the negative...
  15. K

    HELP! Change in GPE and Work Done

    You got it. Just avoid saying Ep is W, rather, say Ep is equal to W. Same goes for W and Ek, or Ep and Ek.
  16. K

    What in the world do I do here?

    Aww man, of coarse. Thank you. I was trying to think about it in terms of photometry.
  17. K

    What in the world do I do here?

    Is there something obvious I'm missing?
  18. K

    Special Relativity!

    oshit. Haha. You're probably right, but I'd still like to know, and I don't have a physics teacher to ask anymore, at least not for a while.
  19. K

    HELP! Change in GPE and Work Done

    I think you've got it, but your wording is a but iffy. Gravitational potential energy isn't energy required for something to happen, it is the potential for energy to be released (as Ek). However, it is equal to the work required to move an object from a point of zero Ep to another position...
  20. K

    Special Relativity!

    This doesn't connote an increase in mass though. Just an increase in density? I tried googling about, and the answer is generally 'Just cus bro'. If I were to take a stab in the dark, I'd say that it has something to do with applied energy v.s. kinetic energy/momentum. Something like: Ek =...
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