General Thoughts: Physics (1 Viewer)

[cutemouse]

Don't we find t_v??? I find t_v
Isn't because if u are moving at fast constant speed, it can also means the space moving at that speed in relative to you too.... :S

No, you find t₀ since from the Earth's frame of reference (ie. t_v) it will take the however many years given in the question for the spacecraft to reach its destination, where as the spacecraft measures less time to get to the destination.

Such an easy mark or so, I can't believe I had a memory blank about this!!!

 

[biopia]

I got that

This question was the hardest for me.
Pretty sure I got the first part right, but the second part was weird.
I found delta y and then found the time for the particle to reach this maximum. I then doubled it.
The indice was -10 though, not +10. God, I hope I didn't completely screw up this question. It was definitely a band 6 type question.

 

[carlytse621]

No, you find t₀ since from the Earth's frame of reference (ie. t_v) it will take the however many years given in the question for the spacecraft to reach its destination, where as the spacecraft measures less time to get to the destination.

Such an easy mark or so, I can't believe I had a memory blank about this!!!

i just checked the jacaranda textbook and it used Tv as well
bt the way i used the wrong unit at the end....it is years not second damn~

 

[Physicswawa]

i thought the paper was overall pretty hard.

Guy's who think its very easy: Don't underestimate the paper. Don't say that i don't warn you if you get 50% raw becuz many people in my grade are saying they are gonna get it and our school is ranked in the top 30 as well (my school name will remain anonymous)

 

[Got2Kno91]

The response to this exam has been very interesting. The people who are talented at math, and are clearly mathematically minded have been calling the exam 'easy' while those which are more english minded (i.e. good at describing/explaining concepts/theories, and other written) found it hard. There are few responses in between. Its either one response or the other.

Unfortunately, i'm better at describe/explain. This exam is the antithesis of the CSSA trial exam (which i did well in). Oh well at least the option topic was easy, and i'm usually not too bad at mc. Core was hard for me though...

 

[darkchild69]

Just read through it, seems like a pretty decent paper. Not all that hard, but a couple of "tricky" questions.

Q2Q is pretty damn easy, just about all my students breezed through that, but some of my students (especially those which do standard maths) had a bit of trouble in the other sections.

MC was a bit of a bitch, some trickily worded questions there.

Half of my students loved the paper, half of them hated it.

So many of them stuffed up Q10 in MC, i have nfi why.

Some interesting discussions over Q5, 13, and 31(e)

I told my guys that the standard model would be the big question in Q2Q, i told them transistors would be in there and that the solar cell/photocell would be in there.

So, im hoping they did alright in those q's!

 

[Physicswawa]

Well our school (remember, ranked top 30) is pretty nerdy at both english and maths. So our school grade overalls says its hard (Even the hardcore maths guys) you guys are gonna do so badly at this trust me.

 

[biopia]

Well our school (remember, ranked top 30) is pretty nerdy at both english and maths. So our school grade overalls says its hard (Even the hardcore maths guys) you guys are gonna do so badly at this trust me.

Let people have their moment.
There's no way of comparing, honestly, even if your school is ranked so high. This site is an environment where high achievers are the predominant 'species'.
And anyway, there seems to be a fair few people who thought it was hard too.
:/

 

[Michaelmoo]

I dont really remember the question too well but how did u get F?

F should equal the force the object exerts due to gravity (since the question said it stops the rotation).

 

[M3riJaan]

Well our school (remember, ranked top 30) is pretty nerdy at both english and maths. So our school grade overalls says its hard (Even the hardcore maths guys) you guys are gonna do so badly at this trust me.

Tell me about it, i was more uncertain than Heisenberg's principle.....

lol not really

Who else didnt realise this..

F=ma
F=mv^2/r
ma=mv^/r
a=v^2/r

i never saw that before the exam...

 

[cutemouse]

i just checked the jacaranda textbook and it used Tv as well

It depends on the question. I assure you that you needed to find t₀ in this particular question in the HSC exam.

 

[boxhunter91]

Tell me about it, i was more uncertain than Heisenberg's principle.....

lol not really

Who else didnt realise this..

F=ma
F=mv^2/r
ma=mv^/r
a=v^2/r

i never saw that before the exam...

I figured it out 2 mins before exam ended..
God what a stupid question..

 

[cutemouse]

I figured it out 2 mins before exam ended..
God what a stupid question..

It's not really stupid... It was covered in depth in Year 11 and it's in some Independent trials (2004 IIRC).

Although I admit, doing Circular Motion in 4U maths did help.

 

[darkchild69]

In that particular question you guys are talking about, it is definately t0, as it is YOUR frame of reference and relative to YOU it is not moving at velocity (hence t0)


Essentially the answer should have come out to be

tv = 170,001.70 years (t = d/s)

t0 = tv (1-(v^2/c^2))^1/2

t0 = 170,001.70(1-(0.99999^2)^1/2

t0 = 760.27y

 

[carlytse621]

In that particular question you guys are talking about, it is definately t0, as it is YOUR frame of reference and relative to YOU it is not moving at velocity (hence t0)


Essentially the answer should have come out to be

tv = 170,001.70 years (t = d/s)

t0 = tv (1-(v^2/c^2))^1/2

t0 = 170,001.70(1-(0.99999^2)^1/2

t0 = 760.27y

o yea....I just realise I didn't use the t formula, instead i used the length formula
so I use find the contracted length first then use this length to find the time
I got the same time as you at the end
however i putted seconds instead of years T_T

 

[M@ster P]

This question was the hardest for me.
Pretty sure I got the first part right, but the second part was weird.
I found delta y and then found the time for the particle to reach this maximum. I then doubled it.
The indice was -10 though, not +10. God, I hope I didn't completely screw up this question. It was definitely a band 6 type question.

I did the same as you but yeah we missed a step, we were suppose to equate ma = qe, find acceleration and then work it out, ( i assumed acceleration was 9.8m/c we should still get 1 or 2 marks though

 

[M@ster P]

In that particular question you guys are talking about, it is definately t0, as it is YOUR frame of reference and relative to YOU it is not moving at velocity (hence t0)


Essentially the answer should have come out to be

tv = 170,001.70 years (t = d/s)

t0 = tv (1-(v^2/c^2))^1/2

t0 = 170,001.70(1-(0.99999^2)^1/2

t0 = 760.27y

I did it this way and I still got the same answer

I did T = d/s

d = from previous question the distance of earth to the galaxy in the spaceship's frame of referecnce

s = 0.9999C

then i calculated T = 760.27

 

[M3riJaan]

is F=qE the same E used in E=v/d ?

 

[study-freak]

I made too many mistakes... 2 multiple choices wrong

and astrophysics option, at least 2 marks off although the last 6 marker (which is supposed to be the herdest question) was easy

 

[study-freak]

I did it this way and I still got the same answer

I did T = d/s

d = from previous question the distance of earth to the galaxy in the spaceship's frame of referecnce

s = 0.9999C

then i calculated T = 760.27

+1 I did this too