The real CONFIRMED mc answers (1 Viewer)

[armenchik]

LOL my teacher said that 12 has two possibly answer either a or b, he said if the majority of the canditature answered a but the "real" answer was b they will still give a mark. Thats good to know.

 

[armenchik]

From someone standing stationaly from earth time will appear to go more SLOWLY on the spacecraft, meaning the time intervals they ON the spacecarft see, (eg. 0.50) will be seen as slower from earth!

Therefore the answer is A!!!!!
Cant beleive so much ppl are so ignorant of the Physical FACTS!

Time tiks SLOWER on moving objects and the question asks, how much time is elapsed on the spacecraft when VIEW FROM EARTH!

To > Tv

!!! 5 is A !!!

 

[Darnie]

how did everyone work out 11? i used F=qvBSinx then used the formula F=(mv^2)/r.
but i couldnt get any of the answers so yeah.
any help?

 

[undalay]

From someone standing stationaly from earth time will appear to go more SLOWLY on the spacecraft, meaning the time intervals they ON the spacecarft see, (eg. 0.50) will be seen as slower from earth!

Therefore the answer is A!!!!!
Cant beleive so much ppl are so ignorant of the Physical FACTS!

Time tiks SLOWER on moving objects and the question asks, how much time is elapsed on the spacecraft when VIEW FROM EARTH!

To > Tv

!!! 5 is A !!!

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"

Now, how would each twin observe the other during the trip? Or, if each twin always carried a clock indicating his age, what time would each see in the image of their distant twin and his clock? The solution to this observational problem can be found in the relativistic Doppler effect. The frequency of clock-ticks which one sees from a source with rest frequency frest is
when the source is moving directly away (a reduction in frequency; "red-shifted").

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).

 

[poisonives]

LOL my teacher said that 12 has two possibly answer either a or b, he said if the majority of the canditature answered a but the "real" answer was b they will still give a mark. Thats good to know.

interesting. that would be good if they paid both

 

[Aaron.Judd]

15 is defiantly D.

 

[poisonives]

15 is defiantly D.

well im not so defiant, lol. can u give us an explanation why, besides the fact that mrs pooviah says so

 

[addikaye03]

The Physics teacher at JRAHS says the answer to 15 is D.

I'll believe that then lol 15/15

 

[Rut Rut]

12 is def B thompson showed the deflection when he balanced magnetic field force and elecrtic field force

 

[jussybussy]

From someone standing stationaly from earth time will appear to go more SLOWLY on the spacecraft, meaning the time intervals they ON the spacecarft see, (eg. 0.50) will be seen as slower from earth!

Therefore the answer is A!!!!!
Cant beleive so much ppl are so ignorant of the Physical FACTS!

Time tiks SLOWER on moving objects and the question asks, how much time is elapsed on the spacecraft when VIEW FROM EARTH!

To > Tv

!!! 5 is A !!!

haha ur calling everyone in this thread ignorant when U DONT EVEN HAVE THE RIGHT ANSWER!!!
ur so wrong! the answer is C.... everyone in this thread agrees and unfortunately, our combined knowledge is a lot more than urs!

 

[jussybussy]

how did everyone work out 11? i used F=qvBSinx then used the formula F=(mv^2)/r.
but i couldnt get any of the answers so yeah.
any help?

the angle of 40 degrees was added in to trick us.... if u look closely, u will see that the electron is actually still entering the magnetic field and crossing the field lines at a perpendicular angle hence sin90 =1 therefore u disregard the value of 40 degrees and the answer becomes D... hope that helped

 

[jussybussy]

I'm with you poisonives, I think that q15 is (b). I'm actually fairly confident. I'm terrible at explaining my thoughts on semiconductors though, so I won't go into it.

For q5, I said (c), but I'm now actualy of the mind that it's (a). My reasoning is that the question asks for the time interval "as measured on Earth", leading me to the belief that the spaceship's time will be t_v, and the Earth's time will be t₀. Subsequent calculations give the answer as (a).

I have a query that I haven't seen discussed yet. For question 7 I said (a), because I thought the magnetic field was fixed in the rotor, and the movement of the rotor created a changing magnetic field with respect to the stator. I didn't think there was a changing magnetic field "in the rotor". Or have I misinterpreted the question?

Thanks =]

the changing magnetic field in the rotor is caused by the surrounding electromagnets inducing a current and hence a magnetic field.....the constant alternation of the currents in the surrounding electromagnets causes the changing magnetic field hence the answer is C

 

[armenchik]

No, not EVERYONE agrees mr. Mabe you should read through it again and chek the other thread.

 

[armenchik]

I'm with you poisonives, I think that q15 is (b). I'm actually fairly confident. I'm terrible at explaining my thoughts on semiconductors though, so I won't go into it.

For q5, I said (c), but I'm now actualy of the mind that it's (a). My reasoning is that the question asks for the time interval "as measured on Earth", leading me to the belief that the spaceship's time will be t_v, and the Earth's time will be t₀. Subsequent calculations give the answer as (a).

I have a query that I haven't seen discussed yet. For question 7 I said (a), because I thought the magnetic field was fixed in the rotor, and the movement of the rotor created a changing magnetic field with respect to the stator. I didn't think there was a changing magnetic field "in the rotor". Or have I misinterpreted the question?

Thanks =]

Nice for you to think that Q5 is (A) becasue it is!
Jesus loves me too :uhhuh:

 

[caso17caso17]

:angry: i got 2,8 and 10 wrong!! but dont get why tehre are problems with 5 it is c and im prety sure 15 is b coz its a flow of positive in valence band which means a flow of electrons in oposite direction in valance band.. hopefuly get a raw mark of 90!!

 

[addikaye03]

Sometimes in Q u can just tell what assessable item they are looking for Q5 was a straight forward application of time dilation, if u read the Q it tells u specifically which is the rest frame etc. Q15 i strongly believe the answer is D, you can just tell that thats what they were testing. B, will not be right.

Also what will 92-95 RAW scale to? like 96-99?

 

[iEdd]

Probably:
92 -> 93/94
95 ->95/96

This is because 100 is 100, 99 is 99 and 98 is 98. There is very little movement in the high end.

 

[addikaye03]

Probably:
92 -> 93/94
95 ->95/96

This is because 100 is 100, 99 is 99 and 98 is 98. There is very little movement in the high end.

Are you sure on that dude? cos an 81 HSC mark in physics on average (depending upon the exam) scales to 90. And my friend believes he got 89 RAW last year and got a 95 HSC MARK. so i was assuming that 92--->97 and 95-> 99.

Im not saying that ur wrong, u maybe right, but just wanted a diff. opinion

 

[iEdd]

Well, obviously not every mark can go up by the same amount. I'm only guessing, but anything over 95 is probably absolute, unless no one gets 100 raw, then 99 might go to 100 and everything else up slightly more.

 

[walk]

Hi iEdd
how do you know about the scaling procedures?