Section I: Part A - Multiple Choice (1 Viewer)

[mynamewastaken]

1 c
2 c
3 b
4 c
5 a
6 a
7 c
8 c
9 b
10 a
11 c
12 b
13 a
14 d
15 a

from you guys' above answers, im pretty sure my 4, 8, 11 and 15 are wrong... and my 5 is different but i still think its right i know i just did the wrong calculation somehow for 11; 15, 8 and 4 i just didnt know.

I couldn't get the answert for q11, got two different answers (using theta= 40 or 50 degrees), but neither were on the multiple choice.

Just put the one closest to the answers, D, which seems right judging by this thread

same, but i picked c i even did qvbsin theta, and then mv^2/r or whatever it is, but somehow screwed up... grrr

 

[snowconesyum]

i'll just say where i got different answers to you -

4 i said A - r proportional to t squared, looks like graph y = root x

7 i put C - changing magnetic field in rotor? was that it?

8 - ok really didn't know, think it was B but i picked cos W and Y were the same but opposite so wouldn't be differenct reallly, and z just looked too random

11 D ? not sure about this. i ignored sin cos i didn't think it was relevant

12 A

13 A ?
14 D???????? dont know

 

[timmiitippii]

For question 4 cannot decide if its A or B
since g is in m/s^2 so it makes sense that the graph should look like A, But B has a line of best fit which my teacher said to always use...
Since a "curve" of best fit requires u to estimate too many points to keep the curve its shape and therefore wont receive valid results. But a Line of best fit is the one satisfying the most points and ignores outliers..
In graph A the line bent to include the last point while B ignores it completely and treats it as an outlier..
So it all depends on if that last point is considered accurate or not...

 

[Kearnzo]

The 40 degrees was not a part of the answer, as the field was directed straight down and the path of the electron was perpendicular to it regardless.

Pretty sure that that 15 is B. Holes are in the valence band.

5 is strange. I don't really know how the Doppler effect would be incorporated into using Einsteins equations. Perhaps it doesnt as we don't learn anything about it.

The clock would be ticking more slowly from the Earth's perspective. So using the Lorentz equation it would be 0.5 / sqrt(1-(0.6^2)) Giving 0.63s.
But also from the Earths perspective the ship is moving away at 1.8 * 10^8 m/s. So the extra distance the light has to travel to reach the earth is equal to 0.3s per click.

I think i have sufficiently confused myself now.

 

[dolbinau]

for 4, use formulas at different heights and you can graph it yourself and see A is correct (IMO.

Snow, 4,7,8,11 - I put this. 12 was B (CHARGED particle, A only says it was a particle i.e have mass but B shows it is a charged particle) 13 was what I got, and D was what I got for 14. So pretty cool .

 

[timmiitippii]

i'll just say where i got different answers to you -

4 i said A - r proportional to t squared, looks like graph y = root x

7 i put C - changing magnetic field in rotor? was that it?

8 - ok really didn't know, think it was B but i picked cos W and Y were the same but opposite so wouldn't be differenct reallly, and z just looked too random

11 D ? not sure about this. i ignored sin cos i didn't think it was relevant

12 A

13 A ?
14 D???????? dont know

14 i said D too coz none of the others made sense. And from only one source where i read this, but i remember reading sumthing about how it doesn't allow the flux lines to penetrate it .. which sounds similar to "excludes magnetic field"

12 im pretty sure its B becoz it showed that cathode rays were charged particles that moved towards positive plate *making them negative* and lead to JJ Thomson using charge paltes to determine charge mass ratio and all that. Just sounds like its more confirmatory than paddle wheel... if both paddle wheel and electric field proves it to be a particle.

 

[snowconesyum]

The clock would be ticking more slowly from the Earth's perspective. So using the Lorentz equation it would be 0.5 / sqrt(1-(0.6^2)) Giving 0.63s.
But also from the Earths perspective the ship is moving away at 1.8 * 10^8 m/s. So the extra distance the light has to travel to reach the earth is equal to 0.3s per click.

I think i have sufficiently confused myself now.

haha i didn't even go into thinking about it in that depth!

however, i think that because it says the time INTERVAL between consecutive pulses, as measured on earth, they don't care about the time lag it would take for the signal arrive, because that time lag would be consistent and so the interval between pulses (even tho it would arrive later) will be the same as whatever we figured out as the time dilation of 0.5 seconds


argh and lame about 12!! i didnt even read the q properly, just recognised it and went YEP that's the paddle wheel debatey thing

 

[cookiemonsterz]

Looks to me like this is what has been decided.
1.c
2.c
3.b
4.a
5.c
6.a
7.c
8.b
9.b
10.a
11.d
12b
13.a
14.d
15.b or d NO ONE KNOWS!!
any 1 got any problems with that?

 

[duy.le]

^ i do, i lost my exam paper and dont remember the answer, can someone post it please.

 

[timmiitippii]

Looks to me like this is what has been decided.
1.c
2.c
3.b
4.a
5.c
6.a
7.c
8.b
9.b
10.a
11.d
12b
13.a
14.d
15.b or d NO ONE KNOWS!!
any 1 got any problems with that?

sweet!! only Q.4 got definitely wrong b =[
with those answers i get 14/15 for mc if 15 is b *which im so positively sure it is*
or 13/15 if its 15.d =[
but i would of been happy with a 12 so its pretty good.

 

[Kearnzo]

haha i didn't even go into thinking about it in that depth!

however, i think that because it says the time INTERVAL between consecutive pulses, as measured on earth, they don't care about the time lag it would take for the signal arrive, because that time lag would be consistent and so the interval between pulses (even tho it would arrive later) will be the same as whatever we figured out as the time dilation of 0.5 seconds


argh and lame about 12!! i didnt even read the q properly, just recognised it and went YEP that's the paddle wheel debatey thing

I think Lorentz equations were derived from the way different frames of reference view each other, so the Doppler effect is incorporated into the equation. So C must be the answer.

Oh no, not reading the questions sucks.

 

[Batesy27]

with question 5 - u just need to use tv as the dilated time on the spaceship and to as the time on earth - this gave (A) 0.4s

 

[wLym]

14 i said D too coz none of the others made sense. And from only one source where i read this, but i remember reading sumthing about how it doesn't allow the flux lines to penetrate it .. which sounds similar to "excludes magnetic field"

12 im pretty sure its B becoz it showed that cathode rays were charged particles that moved towards positive plate *making them negative* and lead to JJ Thomson using charge paltes to determine charge mass ratio and all that. Just sounds like its more confirmatory than paddle wheel... if both paddle wheel and electric field proves it to be a particle.

14 is just the basis of the meissner effect. That a magnetic field cannot penetrate a superconductor because the external magnetic field induces eddy currents in the superconductor, and the magnetic field associated with these eddy currents repel the external magnetic field. walah =) Motors and generators is sinch if u understand all the eddy current crap and motor effect and lenzs law, because if u understand them, then the whole chapter is related ie seems like common knowledge.

12: The Germans thought cathode rays were em waves because they passed through a sheet of gold foil. So it cant be C that resolved it.
Fluorescent glow is just an observation it doesnt resolve anything =S
Cathode rays turning a paddle wheel showed they had momentum and energy but didnt show they were charged particles or not.
Thomson used an electric field deflecting the rays showed they had charge and thus they were negative particles as em waves cannot be deflected in such a way. So it had to be B.
I think thats right and hopefully noone comes along and corrects me lol cause then id kick myself lol.

 

[ziggy.zoozah]

I dont do Phys but apparently the first 3 answers were all C? My friends just had a complain to me about inconsistency in the paper.

 

[dolbinau]

3 was B not C

 

[Daniel-08]

question 5 was C. the real time is the time measured by the person in the spaceship, which is 0.5 seconds. All you have to do now is to substitute into the equation, and the answer is 0.63 (rounded off). This answer is also consistent with time dilation, because the people on Earth observe the time to be longer, wheras the people on the spacecraft observe the time to be shorter.

 

[Aaron.Judd]

I got 13/15. Got no. 2 and no. 4 incorrect.