The real CONFIRMED mc answers (1 Viewer)

[iEdd]

I don't. I was never talking about scaling.

The comments about aligning were purely speculation, but it's common sense that there will be less upward alignment at the high end as that's where the competition is.

 

[walk]

thanx - yes, did mean aligning.... did u talk 2 any of last yrs yr 12 bout what they thgt they got raw and what they ended up with?

 

[iEdd]

Not really. I know of some 2006 *trial* marks, which were comparable standard to the real HSC. 50s went to high 70s. Of course it's hard to tell how much of that was improvement and how much was aligning.

At this point it's basically the waiting game.

 

[addikaye03]

i value ur opinion iEdd. The only thing i dont get is how a guy from my school last yr got 88-89 RAW and ended up with 95 HSC MARK, i practiced on last yrs exam and it looks more straight forward than ours. I still believe 92-95=96-99, obviously it does not go up linearly, but in accordance to the frequency in which that mark is acheived. I spose your right, it is just a waiting game now, i cant wait to see what i get in physics ( hopefully 97-98), maths( i will get 98-100) and PDHPE( hopefully 93-94).. English im kinda restricted (hopefully 82-83), Chemistry ( didnt go great, hopefully 85), MAX1 (hopefully 47/50) wot about u guys?

 

[iEdd]

Yep, I can relate to that. I'm good at science and maths subjects (ideally all band 6s), but hoping to scrape band 5 in English.

 

[uart]

lolz.

Special relativity questions are always subject to confusion and the answer can differ greatly based on how it is worded.
If you want something interesting wikipedia "twins paradox" then scroll down to "What it looks like: the relativistic Doppler shift"



see here:http://en.wikipedia.org/wiki/Twins_paradox#What_it_looks_like:_the_relativistic_Doppler_shift

This formula takes into account both time dilation and relativistic doppler effect, and is almost a perfect match for our question.
According to this formula however. The time interval should slow down from 0.5 seconds to 1 second (according to my calculations).

So i suppose D would be the *most* correct, however the hsc physics syllabus doesn't require us to know about the relativistic doppler effect, and merely time dilation (although it is intertwined) and i suppose it should be 0.63seconds (B).

Ok I know I'm a little late to this thread but thanks undalay, you answered a question I just made in another thread about this mcq (Q5). I got exactly the same answer as you did, 1 second between received pules. It's interesting that the Doppler formula you linked can solve it in one hit, but you don't actually need to use that formula, all that's really needed is to include the time delay of the light getting back to the observer and you can get the correct answer (1 second).

That is, the time between pulses is 0.5 seconds and the additional delay (due to the increasing distance travelled by each consecutive pulse in reaching the observer) is 0.5*v/c = 0.3 seconds. Both of these get time-dilated* and the time dilation factor is 1.25, so the total time between consecutive received pulses is 1.25*(0.5+0.3) = 1 second. I was pretty miffed to find that the correct answer wasn't even listed as one of the mc options.

*PS. It may not be obvious that the additional travel time (0.3 seconds) also gets time dilated but a more complete analysis using the Lorentz transforms shows that it indeed does. In any case if a student attempted to include the extra travel time but didn't realize that it's also dilated then they would still get a much "more correct" answer ( 0.925 seconds) than any of the available mc options. So whatever way you look at it this was a pretty badly planned question by the BOS.