• Best of luck to the class of 2024 for their HSC exams. You got this!
    Let us know your thoughts on the HSC exams here
  • YOU can help the next generation of students in the community!
    Share your trial papers and notes on our Notes & Resources page
MedVision ad

2016ers Chit-Chat Thread (11 Viewers)

Status
Not open for further replies.

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
he said he used 4U mechanics though, so idk what he actually did
he used it to check if it was a curve
The sample answers look somewhat curved. They had corners.

I forgot why that's a corner and not smooth?
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,109
Gender
Male
HSC
N/A
he said he used 4U mechanics though, so idk what he actually did
he used it to check if it was a curve
I'm guessing he used calculus then, 4U mechanics is mostly calculus-based (apart from some circular motion stuff, which doesn't seem relevant for that Q.).
 

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
I'm guessing he used calculus then, 4U mechanics is mostly calculus-based (apart from some circular motion stuff, which doesn't seem relevant for that Q.).
Yeah I couldn't quite puzzle out how mechanics was used for that one.

Was it really that one?
 

Paradoxica

-insert title here-
Joined
Jun 19, 2014
Messages
2,556
Location
Outside reality
Gender
Male
HSC
2016
hypothetical strange situation: x amount of new friends think we are close after one month of concentrated interactions. I have already analysed their personalities and concluded that this friendship cannot hold in the long run.

what is best doings for this person such that there will be no collateral damage and ultimately cutting off friendship?
make up excuses
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,109
Gender
Male
HSC
N/A
Yeah I couldn't quite puzzle out how mechanics was used for that one.

Was it really that one?
It's a combination of resisted motion and the Faraday-Lenz Law I believe.

I see the sample answers didn't explain the curved nature of the graph, although that is probably due to the fact that this actually would need calculus to explain, and that's not assumed knowledge for HSC Physics. For this reason, I think that you'd have gotten the marks even if you'd drawn the line as straight; the main thing they cared about I think was that it was initially steady, then decreased, and then steadied again.

The question would've been even more fun if the copper plate were circular in shape. :)
 
Last edited:

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
It's a combination of resisted motion and the Faraday-Lenz Law I believe.

I see the sample answers didn't explain the curved nature of the graph, although that is probably due to the fact that this actually would need calculus to explain, and that's not assumed knowledge for HSC Physics. For this reason, I think that you'd have gotten the marks even if you'd drawn the line as straight; the main thing they cared about I think was that it was initially steady, then decreased, and then steadied again.
Except whilst induced EMF = -n delta(phi)/delta(t) I'm not sure how you can pull force or acceleration out of it. Probably missed something.
 

Nailgun

Cole World
Joined
Jun 14, 2014
Messages
2,193
Gender
Male
HSC
2016
The sample answers look somewhat curved. They had corners.

I forgot why that's a corner and not smooth?
I think they would have accepted somewhat curved edges assuming it went to straight line quickly, it's just that the force decreases to neglible rates as the distance increases and so the speed returns to a constant

this is because as you get farther away from the magnetic field the strength decreases with distance B = kI/d, and so the deceleration effect from Lenz's Law is diminished

the marking criteria just says show where the velocity is decreasing and constant clearly, so constant at first, decreasing, then constant
 

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
I think they would have accepted somewhat curved edges assuming it went to straight line quickly, it's just that the force decreases to neglible rates as the distance increases and so the speed returns to a constant

this is because as you get farther away from the magnetic field the strength decreases with distance B = kI/d, and so the deceleration effect from Lenz's Law is diminished

the marking criteria just says show where the velocity is decreasing and constant clearly, so constant at first, decreasing, then constant
Of course, when I did the question I also made it clear that it decreased a bit and was constant everywhere else.

Only the corners threw me off when I read their response tbh.
 

Nailgun

Cole World
Joined
Jun 14, 2014
Messages
2,193
Gender
Male
HSC
2016
It's a combination of resisted motion and the Faraday-Lenz Law I believe.

I see the sample answers didn't explain the curved nature of the graph, although that is probably due to the fact that this actually would need calculus to explain, and that's not assumed knowledge for HSC Physics. For this reason, I think that you'd have gotten the marks even if you'd drawn the line as straight; the main thing they cared about I think was that it was initially steady, then decreased, and then steadied again.

The question would've been even more fun if the copper plate were circular in shape. :)
I'm wracking my brain but I don't see how this would make a difference ahaha
care to explain lele


btw
acceleration = -k







Where W is the final speed:p even though k is changing it gave me a rough estimate of what the graph looked like.
 

InteGrand

Well-Known Member
Joined
Dec 11, 2014
Messages
6,109
Gender
Male
HSC
N/A
I'm wracking my brain but I don't see how this would make a difference ahaha
care to explain lele


btw
With the circle thing, I believe it would affect it because the circle's shape means that it as it enters a magnetic field, the area entering is not constant per unit length entered (because cross-sectional lines of a circle aren't constant in length). And ε = –N.dΦ/dt. Since the flux is Φ(t) = B*A(t), the "area entering per unit time" (A(t)) is more complicated with a circle than with a rectangle (which is still non-trivial due to the fact that the copper plate doesn't come in at a constant speed, since it already starts slowing down).
 
Last edited:

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
Ahh... yeah I wouldn't have jumped anywhere near that
 

Nailgun

Cole World
Joined
Jun 14, 2014
Messages
2,193
Gender
Male
HSC
2016
Well there, Drsoccerball assumed the acceleration is a negative constant; this is equivalent to assuming that the velocity graph would be a straight line in the decreasing section.

With the circle thing, I believe it would affect it because the circle's shape means that it as it enters a magnetic field, the area entering is not constant per unit length entered (because cross-sectional lines of a circle aren't constant in length). And ε = –N.dΦ/dt. Since the flux is Φ(t) = B*A(t), the "area entering per unit time" (A(t)) is more complicated with a circle than with a rectangle (which is still non-trivial due to the fact that the copper plate doesn't come in at a constant speed, since it already starts slowing down).
even then though, wouldn't the eddy currents still like 'fill' the whole conducting plate
and so it would still slow down due to their interaction
and then the graph would look the same?
 

WrittenLoveLetters

배고파
Joined
Nov 18, 2014
Messages
1,948
Gender
Female
HSC
2016
Just finished 2U. Had one question (4 marks) that I had to bullshit as much to get maybe 1 or 2 marks. BUT THEN MY DUMBASS IN MC CALCULATED SOMETHING TO BE 8(PI)/3 AND MY DUMBASS CIRCLED THE WRONG ANSWER HEELFSKWLSJALXHSLSHWONWOSW FUCK

I see TAFE at the end of the tunnel //dies
 

Shuuya

Well-Known Member
Joined
Sep 3, 2015
Messages
833
Gender
Undisclosed
HSC
2016
Just finished 2U. Had one question (4 marks) that I had to bullshit as much to get maybe 1 or 2 marks. BUT THEN MY DUMBASS IN MC CALCULATED SOMETHING TO BE 8(PI)/3 AND MY DUMBASS CIRCLED THE WRONG ANSWER HEELFSKWLSJALXHSLSHWONWOSW FUCK

I see TAFE at the end of the tunnel //dies
I labelled x intercepts as (0,something) on one of the easiest graphing questions in the paper ._.
 

StudiousStudent

Active Member
Joined
Feb 20, 2016
Messages
357
Gender
Female
HSC
2016
Just finished 2U. Had one question (4 marks) that I had to bullshit as much to get maybe 1 or 2 marks. BUT THEN MY DUMBASS IN MC CALCULATED SOMETHING TO BE 8(PI)/3 AND MY DUMBASS CIRCLED THE WRONG ANSWER HEELFSKWLSJALXHSLSHWONWOSW FUCK

I see TAFE at the end of the tunnel //dies
Guarantee you performed better than I did in my bio exam yesterday. I actually circled a wrong answer too, and I realised only after the test concluded. It was on sa/vol ffs (only been doing that since year 7).

My teacher is going to be reduced to tears.
 

leehuan

Well-Known Member
Joined
May 31, 2014
Messages
5,805
Gender
Male
HSC
2015
This is why we write student numbers on papers guys. Shh the teachers might not recognise your student number on a multiple choice answer sheet until they give it back

But, I mean, oh dear ._.


Sent from my iPhone using Tapatalk
 

Sien

将来: NEET
Joined
Sep 6, 2014
Messages
2,197
Location
大学入試地獄
Gender
Male
HSC
2016
4.5 pages of bs for English
I hope i can get an ok mark
#pray4sien

Sent from my D6503 using Tapatalk
 
Status
Not open for further replies.

Users Who Are Viewing This Thread (Users: 0, Guests: 11)

Top