General Thoughts: Physics (1 Viewer)

[Life4Never]

Really fair exam imo but 2 things...



It didn't ask about price, so C was actually the best choice because of its efficiency
and also for that length contraction one it was 40.2 cm because it was asking from the electron's point of reference. I came across a question very similar to this one where you had to really think about your reference points
But otherwise I pretty much agree with everything else

Actually it was B. You look at the diagram and work out the power loss for each transmission. A lost 20MW B lost 1.3MW and C lost 3MW(they gave you power needed to keep the line at superconducting temps per km)

And it actually length contracted to 39.8 or somewhere around there. The empty space space is travelling towards you(electron) so it contracts.

Think about this. If you go near c, a stationary observer would see you slowing down, so you can go a large distance with a short amount of time. ie travel light years at times less than a year.
However on the space ship, the universe moves relative to you. So time dilates and length contracts, so you go the same speed but with a shorter distance so the time of travel will be less. This agrees with the above.

So electron is stationary in this case and the screen is moving relative towards it. So the space contracts.
The question specifically said in the electron's perspective.

 

[microsh]

i couldnt resist that angry bird question i drew a pig behind the house

 

[deswa1]

Nice paper all up. The projectile was pretty hard by physics standards but doable. B is the most efficient power, then C, then A. I think for the tower, A falls straight down because it has no initial velocity whilst B goes into geostationary orbit as it carries the initial velocity of the rotation of the Earth.

 

[erckle999]

A fair paper. There seemed to be a greater-than-usual amount of 4/5 markers in Section I B. Not sure about the other options but i felt astrophysics was significantly easier than most years.

 

[microsh]

Nice paper all up. The projectile was pretty hard by physics standards but doable. B is the most efficient power, then C, then A. I think for the tower, A falls straight down because it has no initial velocity whilst B goes into geostationary orbit as it carries the initial velocity of the rotation of the Earth.

for the power question all designs end up providing 100MW
A losses 20MW
B you find I= V/R= 508000/40=12700, Then use power loss equation and you get ~4MW
C is only 30kW*100= 3MW
so C would be the most efficient

 

[Life4Never]

for the power question all designs end up providing 100MW
A losses 20MW
B you find I= V/R= 508000/40=12700, Then use power loss equation and you get ~4MW
C is only 30kW*100= 3MW
so C would be the most efficient

Nah it was B. It lost 8Kv (508 kV to 500kV) and the wire had 40 ohms of resistance. P = IV , V=IR therefore P = V^2 /R = 8000^2 /40 = 1.6 MW
Remember the voltage is the voltage loss not the whole voltage.

Dont know how you got your answer... I subbed your value into P= IV and P= I^2R and still didnt come up with 4MW
I come up with 6451.6MW which is obviously wrong

 

[jenslekman]

A fair paper. There seemed to be a greater-than-usual amount of 4/5 markers in Section I B. Not sure about the other options but i felt astrophysics was significantly easier than most years.

yeah it was - but would've been easier if the 6 marker was a technology question rather than one where we had to use calculations in a written response which was pretty annoying.

 

[mickstarify]

Nah it was B. It lost 8Kv (508 kV to 500kV) and the wire had 40 ohms of resistance. P = IV , V=IR therefore P = V^2 /R = 8000^2 /40 = 1.6 MW
Remember the voltage is the voltage loss not the whole voltage.

Dont know how you got your answer... I subbed your value into P= IV and P= I^2R and still didnt come up with 4MW
I come up with 6451.6MW which is obviously wrong

+1

 

[choiyokbao]

Pretty decent paper, considering the amount of study put in, should get band 5 XD

 

[MonsterMe]

+1

I got this result, with 6451.6 and couldn't figure out what I had done wrong, even though that was a ludicrous answer.. So I crossed it and just..rambled. Got it wrong, obviously =/ Hummf. Oh well.. One more exam

 

[microsh]

Nah it was B. It lost 8Kv (508 kV to 500kV) and the wire had 40 ohms of resistance. P = IV , V=IR therefore P = V^2 /R = 8000^2 /40 = 1.6 MW
Remember the voltage is the voltage loss not the whole voltage.

Dont know how you got your answer... I subbed your value into P= IV and P= I^2R and still didnt come up with 4MW
I come up with 6451.6MW which is obviously wrong

thats because i thought the power loss formula was I^2/R

 

[sodam]

I gunned the Option section so hard!!
Definitely got 14/14 for Section I in quanta!
and 10/11 for Astrophysics Section II
omg hope the other options get moderated down so my mark gets pulled up!

 

[mickstarify]

I gunned the Option section so hard!!
Definitely got 14/14 for Section I in quanta!
and 10/11 for Astrophysics Section II
omg hope the other options get moderated down so my mark gets pulled up!

You did Both? You can do That?

 

[Mr Azul]

You did Both? You can do That?

Yeah man you can! Like I chose the easy ones, but I made sure that I aced them so they wouldn't get
scaled down.

 

[sodam]

Yeah man you can! Like I chose the easy ones, but I made sure that I aced them so they wouldn't get
scaled down.

shiiit thats prety smart man, i didn't think of that! fml
but i guess all that extra study paid off
howd you go in the core!?

 

[mickstarify]

Yeah man you can! Like I chose the easy ones, but I made sure that I aced them so they wouldn't get
scaled down.

Fuck I should have done that, I had no idea how to get 6 marks in Quanta to Quarks for that conservation of energy question

 

[Mr Azul]

Fuck I should have done that, I had no idea how to get 6 marks in Quanta to Quarks for that conservation of energy question

Yeah as soon as I saw that I was like FUCK THAT SHIT. I went straight to the next option to see if it was any better.

 

[Mr Azul]

shiiit thats prety smart man, i didn't think of that! fml
but i guess all that extra study paid off
howd you go in the core!?

The core was pretty tough man. I left some questions out but instead I did extra questions from the option
topics to make up for it.

 

[Life4Never]

The core was pretty tough man. I left some questions out but instead I did extra questions from the option
topics to make up for it.

Hmm what do you mean? You only get marks from one module in the option topic. In the case you did two you only get the marks for your best option. They do not add otherwise there will be people who do multiple option topics and get over 100% (not a good look for the board.)

 

[sodam]

Hmm what do you mean? You only get marks from one module in the option topic. In the case you did two you only get the marks for your best option. They do not add otherwise there will be people who do multiple option topics and get off 100% (not a good look for the board.)

You sure man? I don't think so. That would be EXTREMELY unfair to the average physics student. They're testing their VARIETY and DEPTH of information, and this can only be shown through an attempt of a variety of options including the core.